# Theory Valuation1

theory Valuation1
imports Algebra9
```(**        Valuation1
author Hidetsune Kobayashi
Group You Santo
Department of Mathematics
Nihon University
h_coba@math.cst.nihon-u.ac.jp
June 24, 2005(revised)
July 20, 2007(revised)

chapter 1. elementary properties of a valuation
section 1. definition of a valuation
section 2. the normal valuation of v
section 3. valuation ring
section 4. ideals in a valuation ring
section 5. pow of vp and n_value -- convergence --
section 6. equivalent valuations
section 7. prime divisors
section 8. approximation

**)

theory Valuation1
imports  "Group-Ring-Module.Algebra9"
begin

declare ex_image_cong_iff [simp del]

chapter "Preliminaries"

section "Int and ant (augmented integers)"

lemma int_less_mono:"(a::nat) < b ⟹ int a < int b"
apply simp
done

lemma zless_trans:"⟦(i::int) < j; j < k⟧ ⟹ i < k"
apply simp
done

lemma zmult_pos_bignumTr0:"∃L. ∀m. L < m ⟶ z < x + int m"
by (subgoal_tac "∀m. (nat((abs z) + (abs x))) < m ⟶ z < x + int m",
blast, rule allI, rule impI, arith)

lemma zle_less_trans:"⟦(i::int) ≤ j; j < k⟧ ⟹ i < k"
done

lemma  zless_le_trans:"⟦(i::int) < j; j ≤ k⟧ ⟹ i < k"
done

lemma zmult_pos_bignumTr:"0 < (a::int) ⟹
∃l. ∀m. l < m ⟶ z < x + (int m) * a"
apply (cut_tac zmult_pos_bignumTr0[of "z" "x"])
apply (erule exE)
apply (subgoal_tac "∀m. L < m ⟶ z < x + int m * a", blast)
apply (rule allI, rule impI)
apply (drule_tac a = m in forall_spec, assumption)
apply (subgoal_tac "0 ≤ int m")
apply (frule_tac a = "int m" and b = a in pos_zmult_pos, assumption)
apply (cut_tac order_refl[of "x"])
apply (frule_tac z' = "int m" and z = "int m * a" in
apply (rule_tac y = "x + int m" and z = "x + (int m)* a" in
less_le_trans[of "z"], assumption+)
apply simp
done

lemma  ale_shift:"⟦(x::ant)≤ y; y = z⟧ ⟹ x ≤ z"
by simp

lemma aneg_na_0[simp]:"a < 0 ⟹ na a = 0"

lemma amult_an_an:"an (m * n) = (an m) * (an n)"
done

definition
"x adiv y = ant ((tna x) div (tna y))"

definition
amod :: "[ant, ant] ⇒ ant" (infixl "amod" 200) where
"x amod y = ant ((tna x) mod (tna y))"

lemma apos_amod_conj:"0 < ant b ⟹
0 ≤ (ant a) amod (ant b) ∧ (ant a) amod (ant b) < (ant b)"
by (simp add:amod_def tna_ant, simp only:ant_0[THEN sym],

"(ant a) = (a div b) *⇩a (ant b) + ant (a mod b)"
done

lemma asp_z_Z:"z *⇩a ant x ∈ Z⇩∞"

lemma apos_in_aug_inf:"0 ≤ a ⟹ a ∈ Z⇩∞"
by (simp add:aug_inf_def, rule contrapos_pp, simp+,
cut_tac minf_le_any[of "0"], frule ale_antisym[of "0" "-∞"],
assumption+, simp)

lemma  amult_1_both:"⟦0 < (w::ant); x * w = 1⟧ ⟹ x = 1 ∧ w = 1"
apply (cut_tac mem_ant[of "x"], cut_tac mem_ant[of "w"],
(erule disjE)+, simp,
(frule sym, thin_tac "∞ = 1", simp only:ant_1[THEN sym],
simp del:ant_1))
apply (erule disjE, erule exE, simp,
(frule sym, thin_tac "-∞ = 1", simp only:ant_1[THEN sym],
simp del:ant_1), simp)
apply (frule sym, thin_tac "-∞ = 1", simp only:ant_1[THEN sym],
simp del:ant_1)
apply ((erule disjE)+, erule exE, simp,
frule_tac aless_imp_le[of "0" "-∞"],
cut_tac minf_le_any[of "0"],
frule ale_antisym[of "0" "-∞"], assumption+,
simp only:ant_0[THEN sym], simp,
frule sym, thin_tac "-∞ = 1", simp only:ant_1[THEN sym],
simp del:ant_1)
apply ((erule disjE)+, (erule exE)+, simp only:ant_1[THEN sym],
(cut_tac a = z and b = za in mult.commute, simp,
cut_tac z = za and z' = z in  times_1_both, assumption+),
simp)
apply (erule exE, simp,
cut_tac x = z and y = 0 in less_linear, erule disjE, simp,
frule sym, thin_tac "-∞ = 1", simp only:ant_1[THEN sym],
simp del:ant_1,
frule sym, thin_tac "∞ = 1", simp only:ant_1[THEN sym],
simp del:ant_1,
erule disjE, erule exE, simp,
frule sym, thin_tac "∞ = 1", simp only:ant_1[THEN sym],
simp del:ant_1, simp)
done

lemma poss_int_neq_0:"0 < (z::int) ⟹ z ≠ 0"
by simp

lemma aadd_neg_negg[simp]:"⟦a ≤ (0::ant); b < 0⟧ ⟹ a + b < 0"
apply (frule ale_minus[of "a" "0"], simp,
frule aless_minus[of "b" "0"], simp)
apply (frule aadd_pos_poss[of "-a" "-b"], assumption+,
frule aless_minus[of "0" "-(a + b)"], simp add:a_minus_minus)
done

lemma aadd_two_negg[simp]:"⟦a < (0::ant); b < 0⟧ ⟹ a + b < 0"
by auto

lemma amin_aminTr:"(z::ant) ≤ z' ⟹ amin z w ≤ amin z' w"
(rule impI)+, frule aless_le_trans[of "w" "z" "z'"],
assumption+, simp)

lemma amin_le1:"(z::ant) ≤ z' ⟹ (amin z w) ≤ z'"
rule impI, frule aless_le_trans[of "w" "z" "z'"],

lemma amin_le2:"(z::ant) ≤ z' ⟹ (amin w z) ≤ z'"
frule ale_trans[of "w" "z" "z'"], assumption+)

lemma  Amin_geTr:"(∀j ≤ n. f j ∈ Z⇩∞) ∧ (∀j ≤ n. z ≤ (f j)) ⟶
z ≤ (Amin n f)"
apply (induct_tac n)
apply (rule impI, erule conjE, simp)
apply (rule impI, (erule conjE)+,
cut_tac Nsetn_sub_mem1[of n], simp,
drule_tac x = "Suc n" in spec, simp,
rule_tac z = z and x = "Amin n f" and y = "f(Suc n)" in amin_ge1,
simp+)
done

lemma Amin_ge:"⟦∀j ≤ n. f j ∈ Z⇩∞; ∀j ≤ n. z ≤ (f j)⟧ ⟹
z ≤ (Amin n f)"

definition
Abs :: "ant ⇒ ant" where
"Abs z = (if z < 0 then -z else z)"

lemma Abs_pos:"0 ≤ Abs z"
by (simp add:Abs_def, rule conjI, rule impI,
cut_tac aless_minus[of "z" "0"], simp,
assumption,
rule impI, simp add:aneg_less[of "z" "0"])

lemma Abs_x_plus_x_pos:"0 ≤ (Abs x) + x"
apply (case_tac "x < 0",

done

lemma  Abs_ge_self:"x ≤ Abs x"
cut_tac ale_minus[of "x" "0"],
done

lemma  na_1:"na 1 = Suc 0"
apply (simp only:ant_1[THEN sym], simp only:na_def,
simp only:ant_0[THEN sym], simp only:aless_zless[of "1" "0"],
simp, subgoal_tac "∞ ≠ 1", simp)
apply (simp only:ant_1[THEN sym], simp only:tna_ant,
rule not_sym, simp only:ant_1[THEN sym], simp del:ant_1)
done

lemma ant_int:"ant (int n) = an n"

lemma int_nat:"0 < z ⟹ int (nat z) = z"
by arith

lemma int_ex_nat:"0 < z ⟹ ∃n. int n = z"
by (cut_tac int_nat[of z], blast, assumption)

lemma eq_nat_pos_ints:
"⟦nat (z::int) = nat (z'::int); 0 ≤ z; 0 ≤ z'⟧ ⟹ z = z'"
by simp

lemma a_p1_gt[simp]:"⟦a ≠ ∞; a ≠ -∞⟧  ⟹ a < a + 1"
apply (cut_tac zposs_aposss[of 1], simp)
done

lemma  gt_na_poss:"(na a) < m ⟹ 0 < m"
done

lemma azmult_less:"⟦a ≠ ∞; na a < m; 0 < x⟧
⟹ a < int m *⇩a x"
apply (cut_tac mem_ant[of "a"])
apply (erule disjE)
apply (case_tac "x = ∞") apply simp
apply (subst less_le[of "-∞" "∞"]) apply simp
apply (frule aless_imp_le[of "0" "x"], frule apos_neq_minf[of "x"])
apply (cut_tac mem_ant[of "x"], simp, erule exE, simp)
apply (simp, erule exE, simp)

apply (frule_tac a = "ant z" in gt_na_poss[of _ "m"])
apply (case_tac "x = ∞", simp)
apply (frule aless_imp_le[of "0" "x"])
apply (frule apos_neq_minf[of "x"])
apply (cut_tac mem_ant[of "x"], simp, erule exE,
apply (subst aless_zless)
apply (cut_tac a = "ant z" in gt_na_poss[of _ "m"], assumption)
apply (smt a0_less_int_conv aposs_na_poss int_less_mono int_nat na_def of_nat_0_le_iff pos_zmult_pos tna_ant z_neq_inf)
done

lemma  zmult_gt_one:"⟦2 ≤ m; 0 < xa⟧ ⟹ 1 < int m * xa"
by (metis ge2_zmult_pos mult.commute)

lemma zmult_pos:"⟦ 0 < m; 0 < (a::int)⟧ ⟹ 0 < (int m) * a"
by (frule zmult_zless_mono2[of "0" "a" "int m"], simp, simp)

lemma  ant_int_na:"⟦0 ≤ a; a ≠ ∞ ⟧ ⟹ ant (int (na a)) = a"
by (frule an_na[of "a"], assumption, simp add:an_def)

lemma zpos_nat:"0 ≤ (z::int) ⟹ ∃n. z = int n"
apply (subgoal_tac "z = int (nat z)")
apply blast apply simp
done

section "nsets"

lemma nsetTr1:"⟦j ∈ nset a b; j ≠ a⟧ ⟹ j ∈ nset (Suc a) b"
done

lemma nsetTr2:"j ∈ nset (Suc a) (Suc b) ⟹ j - Suc 0 ∈ nset a b"
done

lemma  nsetTr3:"⟦j ≠ Suc (Suc 0); j - Suc 0 ∈ nset (Suc 0) (Suc n)⟧
⟹  Suc 0 < j - Suc 0"
apply (simp add:nset_def, erule conjE, subgoal_tac "j ≠ 0",
rule contrapos_pp, simp+)
done

lemma Suc_leD1:"Suc m ≤ n ⟹ m < n"
apply (insert lessI[of "m"],
rule less_le_trans[of "m" "Suc m" "n"], assumption+)
done

lemma leI1:"n < m ⟹ ¬ ((m::nat) ≤ n)"
apply (rule contrapos_pp, simp+)
done

lemma neg_zle:"¬ (z::int) ≤ z' ⟹ z' < z"
done

lemma nset_m_m:"nset m m = {m}"
rule equalityI, rule subsetI, simp,
rule subsetI, simp)

lemma nset_Tr51:"⟦j ∈ nset (Suc 0) (Suc (Suc n)); j ≠ Suc 0⟧
⟹ j - Suc 0 ∈ nset (Suc 0) (Suc n)"
frule_tac m = j and n = "Suc (Suc n)" and l = "Suc 0" in diff_le_mono,
simp)
done

lemma nset_Tr52:"⟦j ≠ Suc (Suc 0); Suc 0 ≤ j - Suc 0⟧
⟹ ¬ j - Suc 0 ≤ Suc 0"
by auto

lemma nset_Suc:"nset (Suc 0) (Suc (Suc n)) =
nset (Suc 0) (Suc n) ∪ {Suc (Suc n)}"

lemma AinequalityTr0:"x ≠ -∞ ⟹ ∃L. (∀N. L < N ⟶
(an m) < (x + an N))"
apply (case_tac "x = ∞", simp add:an_def)
apply (cut_tac mem_ant[of "x"], simp, erule exE, simp add:an_def a_zpz,
cut_tac x = z in zmult_pos_bignumTr0[of "int m"], simp)
done

lemma AinequalityTr:"⟦0 < b ∧ b ≠ ∞; x ≠ -∞⟧ ⟹ ∃L. (∀N. L < N ⟶
(an m) < (x + (int N) *⇩a b))"
apply (frule_tac AinequalityTr0[of "x" "m"],
erule exE,
subgoal_tac "∀N. L < N ⟶ an m < x + (int N) *⇩a b",
blast, rule allI, rule impI)
apply (drule_tac a = N in forall_spec, assumption,
erule conjE,
cut_tac N = N in asprod_ge[of "b"], assumption,
thin_tac "x ≠ - ∞", thin_tac "b ≠ ∞", thin_tac "an m < x + an N",
simp)
apply (frule_tac x = "an N" and y = "int N *⇩a b" and z = x in aadd_le_mono,
done

lemma two_inequalities:"⟦∀(n::nat). x < n ⟶ P n; ∀(n::nat). y < n ⟶ Q n⟧
⟹  ∀n. (max x y) < n ⟶ (P n) ∧ (Q n)"
by auto

lemma multi_inequalityTr0:"(∀j ≤ (n::nat). (x j) ≠ -∞ ) ⟶
(∃L. (∀N. L < N ⟶  (∀l ≤ n. (an m) < (x l) + (an N))))"
apply (induct_tac n)
apply (rule impI, simp)
apply (rule AinequalityTr0[of "x 0" "m"], assumption)
(** n **)
apply (rule impI)
apply (subgoal_tac "∀l. l ≤ n ⟶ l ≤ (Suc n)", simp)
apply (erule exE)
apply (frule_tac a = "Suc n" in forall_spec, simp)

apply (frule_tac x = "x (Suc n)" in AinequalityTr0[of _ "m"])
apply (erule exE)
apply (subgoal_tac "∀N. (max L La) < N ⟶
(∀l ≤ (Suc n). an m < x l + an N)", blast)
apply (rule allI, rule impI, rule allI, rule impI)
apply (rotate_tac 1)
apply (case_tac "l = Suc n", simp,
drule_tac m = l and n = "Suc n" in noteq_le_less, assumption+,
drule_tac x = l and n = "Suc n" in less_le_diff, simp,
simp)
done

lemma multi_inequalityTr1:"⟦∀j ≤ (n::nat). (x j) ≠ - ∞⟧ ⟹
∃L. (∀N. L < N ⟶  (∀l ≤ n. (an m) < (x l) + (an N)))"

lemma gcoeff_multi_inequality:"⟦∀N. 0 < N ⟶ (∀j ≤ (n::nat). (x j) ≠ -∞ ∧
0 < (b N j) ∧ (b N j) ≠ ∞)⟧ ⟹
∃L. (∀N. L < N ⟶  (∀l ≤ n.(an m) < (x l) + (int N) *⇩a (b N l)))"
apply (subgoal_tac "∀j ≤ n. x j ≠ - ∞")
apply (frule  multi_inequalityTr1[of "n" "x" "m"])
apply (erule exE)
apply (subgoal_tac "∀N. L < N ⟶
(∀l ≤ n. an m < x l + (int N) *⇩a (b N l))")
apply blast

apply (rule allI, rule impI, rule allI, rule impI,
drule_tac a = N in forall_spec, simp,
drule_tac a = l in forall_spec, assumption,
drule_tac a = N in forall_spec, assumption,
drule_tac a = l in forall_spec, assumption,
drule_tac a = l in forall_spec, assumption)
apply (cut_tac b = "b N l" and N = N in asprod_ge, simp, simp,
(erule conjE)+, simp, thin_tac "x l ≠ - ∞", thin_tac "b N l ≠ ∞")
apply (frule_tac x = "an N" and y = "int N *⇩a b N l" and z = "x l" in
rule allI, rule impI,
cut_tac lessI[of "(0::nat)"],
drule_tac a = "Suc 0" in forall_spec, assumption)
apply simp
done

primrec m_max :: "[nat, nat ⇒ nat] ⇒ nat"
where
m_max_0: "m_max 0 f = f 0"
| m_max_Suc: "m_max (Suc n) f  = max (m_max n f) (f (Suc n))"

(** maximum value of f **)

lemma m_maxTr:"∀l ≤ n. (f l) ≤ m_max n f"
apply (induct_tac n)
apply simp

apply (rule allI, rule impI)
apply simp
apply (case_tac "l = Suc n", simp)
apply (cut_tac m = l and n = "Suc n" in noteq_le_less, assumption+,
thin_tac "l ≤ Suc n", thin_tac "l ≠ Suc n",
frule_tac x = l and n = "Suc n" in less_le_diff,
thin_tac "l < Suc n", simp)
apply (drule_tac a = l in forall_spec, assumption)
apply simp
done

lemma m_max_gt:"l ≤ n ⟹ (f l) ≤ m_max n f"
done

lemma ASum_zero:" (∀j ≤ n. f j ∈ Z⇩∞) ∧ (∀l ≤ n. f l = 0) ⟶ ASum f n = 0"
apply (induct_tac n)
apply (rule impI, erule conjE, simp)
apply (rule impI)
apply (subgoal_tac "(∀j≤n. f j ∈ Z⇩∞) ∧ (∀l≤n. f l = 0)", simp)
thin_tac "(∀j≤n. f j ∈ Z⇩∞) ∧ (∀l≤n. f l = 0) ⟶ ASum f n = 0")
apply (rule conjI)
apply (rule allI, rule impI,
drule_tac a = j in forall_spec, simp, assumption+)
apply (thin_tac "∀j≤Suc n. f j ∈ Z⇩∞")
apply (rule allI, rule impI,
drule_tac a = l in forall_spec, simp+)
done

lemma eSum_singleTr:"(∀j ≤ n. f j ∈ Z⇩∞) ∧ (j ≤ n ∧ (∀l ∈{h. h ≤ n} - {j}. f l = 0))  ⟶ ASum f n = f j"
apply (induct_tac n)
apply (simp, rule impI, (erule conjE)+)
apply (case_tac "j ≤ n")
apply simp
apply simp
apply (frule_tac m = n and n = j in Suc_leI)
apply (frule_tac m = j and n = "Suc n" in le_antisym, assumption+, simp)
apply (cut_tac n = n in ASum_zero [of _ "f"])
apply (subgoal_tac "(∀j≤n. f j ∈ Z⇩∞) ∧ (∀l≤n. f l = 0)")
apply (thin_tac "∀j≤Suc n. f j ∈ Z⇩∞",
thin_tac "∀l∈{h. h ≤ Suc n} - {Suc n}. f l = 0", simp only:mp)

apply (thin_tac "(∀j≤n. f j ∈ Z⇩∞) ∧ (∀l≤n. f l = 0) ⟶ ASum f n = 0")
apply (rule conjI,
thin_tac "∀l∈{h. h ≤ Suc n} - {Suc n}. f l = 0", simp)
apply (thin_tac "∀j≤Suc n. f j ∈ Z⇩∞", simp)
done

lemma eSum_single:"⟦∀j ≤ n. f j ∈ Z⇩∞ ; j ≤ n; ∀l ∈ {h. h ≤ n} - {j}. f l = 0⟧
⟹ ASum  f n = f j"
done

lemma ASum_eqTr:"(∀j ≤ n. f j ∈ Z⇩∞) ∧ (∀j ≤ n. g j ∈ Z⇩∞) ∧
(∀j ≤ n. f j = g j) ⟶ ASum f n = ASum g n"
apply (induct_tac n)
apply (rule impI, simp)

apply (rule impI, (erule conjE)+)
apply simp
done

lemma ASum_eq:"⟦∀j ≤ n. f j ∈ Z⇩∞; ∀j ≤ n. g j ∈ Z⇩∞; ∀j ≤ n. f j = g j⟧ ⟹
ASum f n = ASum g n"
by (cut_tac ASum_eqTr[of n f g], simp)

definition
Kronecker_delta :: "[nat, nat] ⇒ ant"
("(δ⇘_ _⇙)" [70,71]70) where
"δ⇘i j⇙ = (if i = j then 1 else 0)"

definition
K_gamma :: "[nat, nat] ⇒ int"
("(γ⇘_ _⇙)" [70,71]70) where
"γ⇘i j⇙ = (if i = j then 0 else 1)"

abbreviation
TRANSPOS  ("(τ⇘_ _⇙)" [90,91]90) where
"τ⇘i j⇙ == transpos i j"

lemma Kdelta_in_Zinf:"⟦j ≤ (Suc n); k ≤ (Suc n)⟧  ⟹
z *⇩a (δ⇘j k⇙) ∈ Z⇩∞"
done

lemma Kdelta_in_Zinf1:"⟦j ≤ n; k ≤ n⟧  ⟹ δ⇘j k⇙ ∈ Z⇩∞"
apply (rule impI)
apply (simp only:ant_1[THEN sym], simp del:ant_1 add:z_in_aug_inf)
done

primrec m_zmax :: "[nat, nat ⇒ int] ⇒ int"
where
m_zmax_0: "m_zmax 0 f = f 0"
| m_zmax_Suc: "m_zmax (Suc n) f = zmax (m_zmax n f) (f (Suc n))"

lemma m_zmax_gt_eachTr:
"(∀j ≤ n. f j ∈ Zset) ⟶ (∀j ≤ n. (f j) ≤ m_zmax n f)"
apply (induct_tac n)
apply (rule impI, rule allI, rule impI, simp)
apply (rule impI)
apply simp
apply (rule allI, rule impI)
apply (case_tac "j = Suc n", simp)
apply (drule_tac m = j and n = "Suc n" in noteq_le_less, assumption,
drule_tac x = j and n = "Suc n" in less_le_diff, simp)
apply (drule_tac a = j in forall_spec, assumption)
done

lemma m_zmax_gt_each:"(∀j ≤ n. f j ∈ Zset) ⟹ (∀j ≤ n. (f j) ≤ m_zmax n f)"
done

lemma n_notin_Nset_pred:" 0 < n ⟹ ¬ n ≤ (n - Suc 0)"
apply simp
done

lemma Nset_preTr:"⟦0 < n; j ≤ (n - Suc 0)⟧ ⟹ j ≤ n"
apply simp
done

lemma Nset_preTr1:"⟦0 < n; j ≤ (n - Suc 0)⟧ ⟹ j ≠ n"
apply simp
done

lemma transpos_noteqTr:"⟦0 < n; k ≤ (n - Suc 0); j ≤ n; j ≠ n⟧
⟹ j ≠ (τ⇘j n⇙) k"
apply (rule contrapos_pp, simp+)
apply (case_tac "k = j", simp, simp)
apply (case_tac "k = n", simp)
done

chapter "Elementary properties of a valuation"

section "Definition of a valuation"

definition
valuation :: "[('b, 'm) Ring_scheme, 'b ⇒ ant] ⇒ bool" where
"valuation K v ⟷
v ∈ extensional (carrier K) ∧
v ∈ carrier K → Z⇩∞  ∧
v (𝟬⇘K⇙) = ∞ ∧ (∀x∈((carrier K) - {𝟬⇘K⇙}). v x ≠ ∞) ∧
(∀x∈(carrier K). ∀y∈(carrier K). v (x ⋅⇩r⇘K⇙ y) = (v x) + (v y)) ∧
(∀x∈(carrier K). 0 ≤ (v x) ⟶ 0 ≤ (v (1⇩r⇘K⇙ ±⇘K⇙ x))) ∧
(∃x. x ∈ carrier K ∧ (v x) ≠ ∞ ∧ (v x) ≠ 0)"

lemma (in Corps) invf_closed:"x ∈ carrier K - {𝟬} ⟹ x⇗‐ K⇖ ∈ carrier K"
by (cut_tac invf_closed1[of x], simp, assumption)

lemma (in Corps) valuation_map:"valuation K v ⟹ v ∈ carrier K → Z⇩∞"

lemma (in Corps) value_in_aug_inf:"⟦valuation K v; x ∈ carrier K⟧ ⟹
v x ∈ Z⇩∞"

lemma (in Corps) value_of_zero:"valuation K v  ⟹ v (𝟬) = ∞"

lemma (in Corps) val_nonzero_noninf:"⟦valuation K v; x ∈ carrier K; x ≠ 𝟬⟧
⟹ (v x) ≠ ∞"

lemma (in Corps) value_inf_zero:"⟦valuation K v; x ∈ carrier K; v x = ∞⟧
⟹ x = 𝟬"
by (rule contrapos_pp, simp+,
frule val_nonzero_noninf[of v x], assumption+, simp)

lemma (in Corps) val_nonzero_z:"⟦valuation K v; x ∈ carrier K; x ≠ 𝟬⟧ ⟹
∃z. (v x) = ant z"
by (frule value_in_aug_inf[of v x], assumption+,
frule val_nonzero_noninf[of v x], assumption+,
cut_tac mem_ant[of "v x"],  simp add:aug_inf_def)

lemma (in Corps) val_nonzero_z_unique:"⟦valuation K v; x ∈ carrier K; x ≠ 𝟬⟧
⟹ ∃!z. (v x) = ant z"
by (rule ex_ex1I, simp add:val_nonzero_z, simp)

lemma (in Corps) value_noninf_nonzero:"⟦valuation K v; x ∈ carrier K; v x ≠ ∞⟧
⟹ x ≠ 𝟬"
by (rule contrapos_pp, simp+, simp add:value_of_zero)

lemma (in Corps) val1_neq_0:"⟦valuation K v; x ∈ carrier K; v x = 1⟧ ⟹
x ≠ 𝟬"
apply (rule contrapos_pp, simp+, simp add:value_of_zero)
apply (simp only:ant_1[THEN sym], cut_tac z_neq_inf[THEN not_sym, of 1], simp)
done

lemma (in Corps) val_Zmin_sym:"⟦valuation K v; x ∈ carrier K; y ∈ carrier K⟧
⟹  amin (v x) (v y) = amin (v y ) (v x)"

lemma (in Corps) val_t2p:"⟦valuation K v; x ∈ carrier K; y ∈ carrier K⟧
⟹ v (x ⋅⇩r y ) = v x + v y"

lemma (in Corps) val_axiom4:"⟦valuation K v; x ∈ carrier K; 0 ≤ v x⟧ ⟹
0 ≤ v (1⇩r ± x)"

lemma (in Corps) val_axiom5:"valuation K v ⟹
∃x. x ∈ carrier K ∧ v x ≠ ∞ ∧ v x ≠ 0"

lemma (in Corps) val_field_nonzero:"valuation K v ⟹ carrier K ≠ {𝟬}"
by (rule contrapos_pp, simp+,
frule val_axiom5[of v],
erule exE, (erule conjE)+, simp add:value_of_zero)

lemma (in Corps) val_field_1_neq_0:"valuation K v ⟹ 1⇩r ≠ 𝟬"
apply (rule contrapos_pp, simp+)
apply (frule val_axiom5[of v])
apply (erule exE, (erule conjE)+)
apply (cut_tac field_is_ring,
frule_tac t = x in  Ring.ring_l_one[THEN sym, of "K"], assumption+,
done

lemma (in Corps) value_of_one:"valuation K v ⟹ v (1⇩r) = 0"
apply (cut_tac field_is_ring, frule Ring.ring_one[of "K"])
apply (frule val_t2p[of v "1⇩r" "1⇩r"], assumption+,
frule val_nonzero_z[of v "1⇩r"], assumption+,
done

lemma (in Corps) has_val_one_neq_zero:"valuation K v ⟹ 1⇩r ≠ 𝟬"
by (frule value_of_one[of "v"],

lemma (in Corps) val_minus_one:"valuation K v ⟹ v (-⇩a 1⇩r) = 0"
apply (cut_tac field_is_ring, frule Ring.ring_one[of "K"],
frule Ring.ring_is_ag[of "K"],
frule val_field_1_neq_0[of v],
frule aGroup.ag_inv_inj[of "K" "1⇩r" "𝟬"], assumption+,
apply (frule val_nonzero_z[of v "-⇩a 1⇩r"],
erule exE, frule val_t2p [THEN sym, of v "-⇩a 1⇩r" "-⇩a 1⇩r"])
frule Ring.ring_inv1_3[THEN sym, of "K" "1⇩r" "1⇩r"], assumption+,
done

lemma (in Corps) val_minus_eq:"⟦valuation K v; x ∈ carrier K⟧ ⟹
v (-⇩a x) = v x"
apply (cut_tac field_is_ring,
subst val_t2p[of v], assumption+,
frule Ring.ring_is_ag[of "K"], rule aGroup.ag_mOp_closed, assumption+,
done

lemma (in Corps) value_of_inv:"⟦valuation K v; x ∈ carrier K; x ≠ 𝟬⟧ ⟹
v (x⇗‐K⇖) = - (v x)"
apply (cut_tac invf_inv[of x], erule conjE,
frule val_t2p[of v "x⇗‐K⇖" x], assumption+,
apply simp
done

lemma (in Corps) val_exp_ring:"⟦ valuation K v; x ∈ carrier K; x ≠ 𝟬⟧
⟹ (int n) *⇩a (v x) = v (x^⇗K n⇖)"
apply (cut_tac field_is_ring,
apply (drule sym, simp)
apply (subst val_t2p[of v _ x], assumption+,
rule Ring.npClose, assumption+,
frule val_nonzero_z[of v x], assumption+,
done

text‹exponent in a field›
lemma (in Corps) val_exp:"⟦ valuation K v; x ∈ carrier K; x ≠ 𝟬⟧ ⟹
z *⇩a (v x) = v (x⇘K⇙⇗z⇖)"
apply (case_tac "0 ≤ z",
simp, frule val_exp_ring [of v x "nat z"], assumption+,
simp, simp)
cut_tac invf_closed1[of x], simp,
cut_tac  val_exp_ring [THEN sym, of v "x⇗‐ K⇖" "nat (- z)"], simp,
thin_tac "v (x⇗‐ K⇖^⇗K (nat (- z))⇖) = (- z) *⇩a v (x⇗‐ K⇖)", erule conjE)
apply (subst value_of_inv[of v x], assumption+)
apply (frule val_nonzero_z[of v x], assumption+, erule exE, simp,
done

lemma (in Corps) value_zero_nonzero:"⟦valuation K v; x ∈ carrier K; v x = 0⟧
⟹ x ≠ 𝟬"
by (frule value_noninf_nonzero[of v x], assumption+, simp,
assumption)

lemma (in Corps) v_ale_diff:"⟦valuation K v; x ∈ carrier K; y ∈ carrier K;
x ≠ 𝟬; v x ≤ v y ⟧ ⟹ 0 ≤ v(y ⋅⇩r x⇗‐ K⇖)"
apply (frule value_in_aug_inf[of v x], simp+,
frule value_in_aug_inf[of v y], simp+,
frule val_nonzero_z[of v x], assumption+,
erule exE)
apply (cut_tac invf_closed[of x], simp+,
frule_tac x = "ant z" in ale_diff_pos[of _ "v y"],
apply simp
done

lemma (in Corps) amin_le_plusTr:"⟦valuation K v; x ∈ carrier K; y ∈ carrier K;
v x ≠ ∞; v y ≠ ∞; v x ≤ v y⟧ ⟹ amin (v x) (v y) ≤ v ( x ± y)"
apply (cut_tac field_is_ring, frule Ring.ring_is_ag,
frule value_noninf_nonzero[of v x], assumption+,
frule v_ale_diff[of v x y], assumption+,
cut_tac invf_closed1[of x],
frule Ring.ring_tOp_closed[of K y "x⇗‐ K⇖"], assumption+, simp,
frule Ring.ring_one[of "K"],
frule aGroup.ag_pOp_closed[of "K" "1⇩r" "y ⋅⇩r x⇗‐ K⇖"], assumption+,
frule val_axiom4[of v "y ⋅⇩r ( x⇗‐ K⇖)"], assumption+)
apply (frule aadd_le_mono[of "0" "v (1⇩r ± y ⋅⇩r x⇗‐ K⇖)" "v x"],
simp add:val_t2p[THEN sym, of v x],
cut_tac amin_le_l[of "v x" "v y"],
rule ale_trans[of "amin (v x) (v y)" "v x" "v (x ± y)"], assumption+)
apply simp
done

lemma (in Corps) amin_le_plus:"⟦valuation K v; x ∈ carrier K; y ∈ carrier K⟧
⟹ (amin (v x) (v y)) ≤ (v (x ± y))"
apply (cut_tac field_is_ring, frule Ring.ring_is_ag)
apply (case_tac "v x = ∞ ∨ v y = ∞")
apply (erule disjE, simp,
frule value_inf_zero[of v x], assumption+,
frule value_inf_zero[of v y], assumption+,
simp add:aGroup.ag_r_zero amin_def, simp, erule conjE)
apply (cut_tac z = "v x" and w = "v y" in ale_linear,
frule_tac amin_le_plusTr[of v y x], assumption+,
done

lemma (in Corps) value_less_eq:"⟦ valuation K v; x ∈ carrier K; y ∈ carrier K;
(v x) < (v y)⟧ ⟹ (v x) = (v (x ± y))"
apply (cut_tac field_is_ring, frule Ring.ring_is_ag[of "K"],
frule amin_le_plus[of v x y], assumption+,
frule aless_imp_le[of "v x" "v y"],
apply (frule amin_le_plus[of v "x ± y" "-⇩a y"],
rule aGroup.ag_pOp_closed, assumption+,
rule aGroup.ag_mOp_closed, assumption+,
frule aGroup.ag_mOp_closed[of "K" "y"], assumption+,
apply (case_tac "¬ (v (x ±⇘K⇙ y) ≤ (v y))", simp+)
done

lemma (in Corps) value_less_eq1:"⟦valuation K v; x ∈ carrier K; y ∈ carrier K;
(v x) < (v y)⟧ ⟹ v x =  v (y ± x)"
apply (cut_tac field_is_ring,
frule Ring.ring_is_ag[of "K"],
frule value_less_eq[of v x y], assumption+)
apply (subst aGroup.ag_pOp_commute, assumption+)
done

lemma (in Corps) val_1px:"⟦valuation K v; x ∈ carrier K; 0 ≤ (v (1⇩r ± x))⟧
⟹ 0 ≤ (v x)"
apply (cut_tac field_is_ring, frule Ring.ring_is_ag[of "K"],
frule Ring.ring_one[of "K"])
apply (rule contrapos_pp, simp+,
case_tac "x = 𝟬⇘K⇙",
simp add: aneg_le[of "0" "v x"],
frule value_less_eq[of v x "1⇩r"], assumption+,
apply (drule sym,
done

lemma (in Corps) val_1mx:"⟦valuation K v; x ∈ carrier K;
0 ≤ (v (1⇩r ± (-⇩a x)))⟧ ⟹ 0 ≤ (v x)"
by (cut_tac field_is_ring, frule Ring.ring_is_ag[of "K"],
frule val_1px[of v "-⇩a x"],

section "The normal valuation of v"

definition
Lv :: "[('r, 'm) Ring_scheme , 'r ⇒ ant] ⇒ ant" (* Least nonnegative value *) where
"Lv K v = AMin {x. x ∈ v ` carrier K ∧ 0 < x}"

definition
n_val :: "[('r, 'm) Ring_scheme, 'r ⇒ ant] ⇒ ('r ⇒ ant)" where
"n_val K v = (λx∈ carrier K.  (THE l. (l * (Lv K v)) = v x))"
(* normal valuation *)

definition
Pg :: "[('r, 'm) Ring_scheme, 'r ⇒ ant] ⇒ 'r" (* Positive generator *) where
"Pg K v = (SOME x. x ∈ carrier K - {𝟬⇘K⇙} ∧ v x = Lv K v)"

lemma (in Corps) vals_pos_nonempty:"valuation K v ⟹
{x. x ∈ v ` carrier K ∧ 0 < x} ≠ {}"
using val_axiom5[of v] value_noninf_nonzero[of v] value_of_inv[THEN sym, of v]
by (auto simp: ex_image_cong_iff) (metis Ring.ring_is_ag aGroup.ag_mOp_closed aGroup.ag_pOp_closed aGroup.ag_r_inv1 f_is_ring zero_lt_inf)

lemma (in Corps) vals_pos_LBset:"valuation K v ⟹
{x. x ∈ v ` carrier K ∧ 0 < x} ⊆ LBset 1"
by (rule subsetI, simp add:LBset_def, erule conjE,
rule_tac x = x in gt_a0_ge_1, assumption)

lemma (in Corps) Lv_pos:"valuation K v ⟹ 0 < Lv K v"
frule vals_pos_nonempty[of v],
frule vals_pos_LBset[of v],
simp only:ant_1[THEN sym],
frule AMin[of "{x. x ∈ v ` carrier K ∧ 0 < x}" "1"], assumption+,
erule conjE)
apply simp
done

lemma (in Corps) AMin_z:"valuation K v ⟹
∃a. AMin {x. x ∈ v ` carrier K ∧ 0 < x} = ant a"
apply (frule vals_pos_nonempty[of v],
frule vals_pos_LBset[of v],
simp only:ant_1[THEN sym],
frule AMin[of "{x. x ∈ v ` carrier K ∧ 0 < x}" "1"], assumption+,
erule conjE)
apply (frule val_axiom5[of v],
erule exE, (erule conjE)+,
cut_tac x = "v x" in aless_linear[of _ "0"], simp,
erule disjE,
frule_tac x = x in value_noninf_nonzero[of v], assumption+,
frule_tac x1 = x in value_of_inv[THEN sym, of v], assumption+)
apply (frule_tac x = "v x" in aless_minus[of _ "0"], simp,
cut_tac x = x in invf_closed1, simp, erule conjE,
frule valuation_map[of v],
frule_tac a = "x⇗‐ K⇖" in mem_in_image[of "v" "carrier K" "Z⇩∞"], simp)
apply (drule_tac a = "v (x⇗‐ K⇖)" in forall_spec, simp,
frule_tac x = "x⇗‐ K⇖" in val_nonzero_noninf[of v],
thin_tac "v (x⇗‐ K⇖) ∈ v ` carrier K",
thin_tac "{x ∈ v ` carrier K. 0 < x} ⊆ LBset 1",
thin_tac "AMin {x ∈ v ` carrier K. 0 < x} ∈ v ` carrier K",
thin_tac "0 < AMin {x ∈ v ` carrier K. 0 < x}", simp,
thin_tac "v (x⇗‐ K⇖) ∈ v ` carrier K",
thin_tac "{x ∈ v ` carrier K. 0 < x} ⊆ LBset 1",
thin_tac "AMin {x ∈ v ` carrier K. 0 < x} ∈ v ` carrier K",
thin_tac "0 < AMin {x ∈ v ` carrier K. 0 < x}", simp)
apply (rule noninf_mem_Z[of "AMin {x ∈ v ` carrier K. 0 < x}"],
frule image_sub[of v "carrier K" "Z⇩∞" "carrier K"],
rule subset_refl)
apply (rule subsetD[of "v ` carrier K" "Z⇩∞"
"AMin {x ∈ v ` carrier K. 0 < x}"], assumption+)
apply auto
by (metis (no_types, lifting) aneg_le aug_inf_noninf_is_z image_eqI value_in_aug_inf z_less_i)

lemma (in Corps) Lv_z:"valuation K v ⟹ ∃z. Lv K v = ant z"
by (simp add:Lv_def, rule AMin_z, assumption+)

lemma (in Corps) AMin_k:"valuation K v ⟹
∃k∈ carrier K - {𝟬}. AMin {x. x ∈ v ` carrier K ∧ 0 < x} = v k"

apply (frule vals_pos_nonempty[of v],
frule vals_pos_LBset[of v],
simp only:ant_1[THEN sym],
frule AMin[of "{x. x ∈ v ` carrier K ∧ 0 < x}" "1"], assumption+,
erule conjE)
apply (thin_tac "∀x∈{x. x ∈ v ` carrier K ∧ 0 < x}.
AMin {x. x ∈ v ` carrier K ∧ 0 < x} ≤ x")
apply (simp add:image_def, erule conjE, erule bexE,
thin_tac "{x. (∃xa∈carrier K. x = v xa) ∧ 0 < x} ⊆ LBset 1",
thin_tac "∃x. (∃xa∈carrier K. x = v xa) ∧ 0 < x",
subgoal_tac "x ∈ carrier K - {𝟬}", blast,
frule AMin_z[of v],  erule exE, simp)
thin_tac "AMin {x. (∃xa∈carrier K. x = v xa) ∧ 0 < x} = ant a",
rule contrapos_pp, simp+, frule sym, thin_tac "v (𝟬) = ant a",
done

lemma (in Corps) val_Pg:" valuation K v ⟹
Pg K v ∈ carrier K - {𝟬} ∧ v (Pg K v) = Lv K v"
apply (frule AMin_k[of v], unfold Lv_def, unfold Pg_def)
apply (rule someI2_ex)
apply (erule bexE, drule sym, unfold Lv_def, blast)
apply simp
done

lemma (in Corps) amin_generateTr:"valuation K v ⟹
∀w∈carrier K - {𝟬}. ∃z. v w = z *⇩a AMin {x. x ∈ v ` carrier K ∧ 0 < x}"
apply (frule vals_pos_nonempty[of v],
frule vals_pos_LBset[of v],
simp only:ant_1[THEN sym],
frule AMin[of "{x. x ∈ v ` carrier K ∧ 0 < x}" "1"], assumption+,
frule AMin_z[of v], erule exE, simp,
thin_tac "∃x. x ∈ v ` carrier K ∧ 0 < x",
(erule conjE)+, rule ballI, simp, erule conjE,
frule_tac x = w in val_nonzero_noninf[of v], assumption+,
frule_tac x = w in value_in_aug_inf[of v], assumption+,
cut_tac a = "v w" in mem_ant, simp, erule exE,
cut_tac a = z and b = a in amod_adiv_equality)
thin_tac "{x. x ∈ v ` carrier K ∧ 0 < x} ⊆ LBset 1",
thin_tac "v w ≠ ∞", thin_tac "v w ≠ - ∞")

apply (frule AMin_k[of v], erule bexE,
drule sym,
drule sym,
drule sym,
rotate_tac -1, drule sym)

apply (cut_tac z = z in z_in_aug_inf,
cut_tac z = "(z div a)" and x = a in asp_z_Z,
cut_tac z = "z mod a" in z_in_aug_inf,
frule_tac a = "ant z" and b = "(z div a) *⇩a ant a" and
c = "ant (z mod a)" in ant_sol, assumption+,
subst asprod_mult, simp, assumption, simp,
frule_tac x = k and z = "z div a" in val_exp[of v],
(erule conjE)+, assumption, simp, simp,
thin_tac "(z div a) *⇩a v k = v (k⇘K⇙⇗(z div a)⇖)",
erule conjE)
apply (frule_tac x = k and n = "z div a" in field_potent_nonzero1,
assumption+,
frule_tac a = k and n = "z div a" in npowf_mem, assumption,
frule_tac x1 = "k⇘K⇙⇗(z div a)⇖" in value_of_inv[THEN sym, of v], assumption+,
thin_tac "- v (k⇘K⇙⇗(z div a)⇖) = v ((k⇘K⇙⇗(z div a)⇖)⇗‐ K⇖)",
cut_tac x = "k⇘K⇙⇗(z div a)⇖" in invf_closed1, simp,
simp, erule conjE,
frule_tac x1 = w and y1 = "(k⇘K⇙⇗(z div a)⇖)⇗‐ K⇖"  in
val_t2p[THEN sym, of  v], assumption+, simp,
cut_tac field_is_ring,
thin_tac "v w + v ((k⇘K⇙⇗(z div a)⇖)⇗‐ K⇖) = ant (z mod a)",
thin_tac "v (k⇘K⇙⇗(z div a)⇖) + ant (z mod a) = v w",
frule_tac x = w and y = "(k⇘K⇙⇗(z div a)⇖)⇗‐ K⇖" in
Ring.ring_tOp_closed[of "K"], assumption+)
apply (frule valuation_map[of v],
frule_tac a = "w ⋅⇩r (k⇘K⇙⇗(z div a)⇖)⇗‐ K⇖" in mem_in_image[of "v"
"carrier K" "Z⇩∞"], assumption+, simp)
apply (thin_tac "AMin {x. x ∈ v ` carrier K ∧ 0 < x} = v k",
thin_tac "v ∈ carrier K → Z⇩∞",
subgoal_tac "0 < v (w ⋅⇩r (k⇘K⇙⇗(z div a)⇖)⇗‐ K⇖ )",
drule_tac a = "v (w ⋅⇩r (k⇘K⇙⇗(z div a)⇖)⇗‐ K⇖)" in forall_spec,
apply (drule sym, simp)
apply (frule_tac b = a and a = z in pos_mod_conj, erule conjE,
simp, simp,
frule_tac b = a and a = z in pos_mod_conj, erule conjE, simp)
done

lemma (in Corps) val_principalTr1:"⟦ valuation K v⟧  ⟹
Lv K v ∈ v ` (carrier K - {𝟬}) ∧
(∀w∈v ` carrier K. ∃a. w = a * Lv K v) ∧ 0 < Lv K v"
apply (rule conjI,
frule val_Pg[of v], erule conjE,
simp add:image_def, frule sym, thin_tac "v (Pg K v) = Lv K v",
erule conjE, blast)
apply (rule conjI,
rule ballI, simp add:image_def, erule bexE)

apply  (
frule_tac x = x in value_in_aug_inf[of v], assumption,
frule sym, thin_tac "w = v x", simp add:aug_inf_def,
cut_tac a = w in mem_ant, simp, erule disjE, erule exE,
frule_tac x = x in value_noninf_nonzero[of v], assumption+,
simp, frule amin_generateTr[of v])
apply (drule_tac x = x in bspec, simp,
erule exE,
frule AMin_z[of v], erule exE, simp add:Lv_def,
simp add:asprod_mult, frule sym, thin_tac "za * a = z",
simp, subst a_z_z[THEN sym], blast)

frule AMin_z[of v], erule exE, simp,
frule_tac m1 = a in a_i_pos[THEN sym], blast,
done

lemma (in Corps) val_principalTr2:"⟦valuation K v;
c ∈ v ` (carrier K - {𝟬}) ∧ (∀w∈v ` carrier K. ∃a. w = a * c) ∧ 0 < c;
d ∈ v ` (carrier K - {𝟬}) ∧ (∀w∈v ` carrier K. ∃a. w = a * d) ∧ 0 < d⟧
⟹ c = d"
apply ((erule conjE)+,
drule_tac x = d in bspec,
drule_tac x = c in bspec,

apply ((erule exE)+,
drule sym, simp,
(erule conjE)+,
frule_tac x = x in val_nonzero_z[of v], assumption+, erule exE,
frule_tac x = xa in val_nonzero_z[of v], assumption+, erule exE,
simp) apply (
subgoal_tac "a ≠ ∞ ∧ a ≠ -∞", subgoal_tac "aa ≠ ∞ ∧ aa ≠ -∞",
cut_tac a = a in mem_ant, cut_tac a = aa in mem_ant, simp,
thin_tac "c = ant z", frule sym, thin_tac "zb * z = za", simp)
apply (subgoal_tac "0 < zb",
cut_tac a = zc and b = zb in mult.commute, simp,
rule contrapos_pp, simp+,
cut_tac x = 0 and y = zb in less_linear, simp,
thin_tac "¬ 0 < zb",
erule disjE, simp,
frule_tac i = 0 and j = z and k = zb in zmult_zless_mono_neg,
apply (rule contrapos_pp, simp+, thin_tac "a ≠ ∞ ∧ a ≠ - ∞",
erule disjE, simp, rotate_tac 5, drule sym,
simp, simp, rotate_tac 5, drule sym, simp)
apply (rule contrapos_pp, simp+,
erule disjE, simp, rotate_tac 4,
drule sym, simp, simp,
rotate_tac 4, drule sym,
simp)
done

lemma (in Corps) val_principal:"valuation K v ⟹
∃!x0. x0 ∈ v ` (carrier K - {𝟬}) ∧
(∀w ∈ v ` (carrier K). ∃(a::ant). w = a * x0) ∧ 0 < x0"
by (rule ex_ex1I,
frule val_principalTr1[of v], blast,
rule_tac c = x0 and d = y in val_principalTr2[of v],
assumption+)

lemma (in Corps) n_val_defTr:"⟦valuation K v; w ∈ carrier K⟧ ⟹
∃!a. a * Lv K v = v w"
apply (rule ex_ex1I,
frule AMin_k[of v],
erule bexE,
frule_tac x = k in val_nonzero_z[of v], simp, simp,
erule exE, simp, (erule conjE)+)
apply (case_tac "w = 𝟬⇘K⇙", simp add:value_of_zero,
frule_tac m = z in a_i_pos, blast)
apply (frule amin_generateTr[of v],
drule_tac x = w in bspec, simp, simp)
apply (
subst a_z_z[THEN sym], blast)
apply (frule AMin_k[of v]) apply (erule bexE,
frule Lv_pos[of v], simp add:Lv_def) apply (
erule conjE,
frule_tac x = k in val_nonzero_z[of v], assumption+,
erule exE, simp) apply (
case_tac "w = 𝟬⇘K⇙", simp del:a_i_pos add:value_of_zero,
subgoal_tac "y = ∞", simp, rule contrapos_pp, simp+,
cut_tac a = a in mem_ant, simp,
erule disjE, simp, erule exE, simp add:a_z_z)
apply (rule contrapos_pp, simp+,
cut_tac a = y in mem_ant, simp, erule disjE, simp,
frule_tac x = w in val_nonzero_z[of v], assumption+,
erule exE, simp, cut_tac a = a in mem_ant,
erule disjE, simp, frule sym, thin_tac "- ∞ = ant za", simp,
erule disjE, erule exE, simp add:a_z_z)
apply (cut_tac a = y in mem_ant,
erule disjE, simp, rotate_tac 3, drule sym,
simp, erule disjE, erule exE, simp add:a_z_z, frule sym,
thin_tac "zb * z = za", simp, simp,
rotate_tac 3, drule sym,
simp, simp, frule sym, thin_tac "∞ = ant za", simp)
done

lemma (in Corps) n_valTr:"⟦ valuation K v; x ∈ carrier K⟧  ⟹
(THE l. (l * (Lv K v)) = v x)*(Lv K v) = v x"
by (rule theI', rule n_val_defTr, assumption+)

lemma (in Corps) n_val:"⟦valuation K v; x ∈ carrier K⟧  ⟹
(n_val K v x)*(Lv K v) = v x"
by (frule n_valTr[of v x], assumption+, simp add:n_val_def)

lemma (in Corps) val_pos_n_val_pos:"⟦valuation K v; x ∈ carrier K⟧  ⟹
(0 ≤ v x) = (0 ≤ n_val K v x)"
apply (frule n_val[of v x], assumption+,
drule sym,
frule Lv_pos[of v],
frule Lv_z[of v], erule exE, simp)
apply (frule_tac w = z and x = 0 and y = "n_val K v x" in amult_pos_mono_r,
done

lemma (in Corps) n_val_in_aug_inf:"⟦valuation K v; x ∈ carrier K⟧ ⟹
n_val K v x ∈ Z⇩∞"
apply (cut_tac field_is_ring, frule Ring.ring_zero[of "K"],
frule Lv_pos[of v],
frule Lv_z[of v], erule exE,
apply (rule contrapos_pp, simp+)
apply (case_tac "x = 𝟬⇘K⇙", simp,
frule n_val[of v "𝟬"],

apply (frule n_val[of v x], simp,
frule val_nonzero_z[of v x], assumption+,
erule exE, simp, rotate_tac -2, drule sym,
simp)
done

lemma (in Corps) n_val_0:"⟦valuation K v; x ∈ carrier K; v x = 0⟧
⟹  n_val K v x = 0"
by (frule Lv_z[of v], erule exE,
frule Lv_pos[of v],
frule n_val[of v x], simp, simp,
rule_tac z = z and a = "n_val K v x" in a_a_z_0, assumption+)

lemma (in Corps) value_n0_n_val_n0:"⟦valuation K v; x ∈ carrier K; v x ≠ 0⟧ ⟹
n_val K v x ≠ 0"
apply (frule n_val[of v x],
rule contrapos_pp, simp+, frule Lv_z[of v],
erule exE, simp, simp only:ant_0[THEN sym])
apply (rule contrapos_pp, simp+,
done

lemma (in Corps) val_0_n_val_0:"⟦valuation K v; x ∈ carrier K⟧ ⟹
(v x = 0) = (n_val K v x = 0)"
apply (rule iffI,
apply (rule contrapos_pp, simp+,
frule value_n0_n_val_n0[of v x], assumption+)
apply simp
done

lemma (in Corps) val_noninf_n_val_noninf:"⟦valuation K v; x ∈ carrier K⟧ ⟹
(v x ≠ ∞) = (n_val K v x ≠ ∞)"
by (frule Lv_z[of v], erule exE,
frule Lv_pos[of v], simp,
frule n_val[THEN sym, of v x],simp, simp,
thin_tac "v x = n_val K v x * ant z",
rule iffI, rule contrapos_pp, simp+,
cut_tac mem_ant[of "n_val K v x"], erule disjE, simp,
erule disjE, erule exE, simp add:a_z_z, simp, simp)

lemma (in Corps) val_inf_n_val_inf:"⟦valuation K v; x ∈ carrier K⟧ ⟹
(v x = ∞) = (n_val K v x = ∞)"
by (cut_tac val_noninf_n_val_noninf[of v x], simp, assumption+)

lemma (in Corps) val_eq_n_val_eq:"⟦valuation K v; x ∈ carrier K; y ∈ carrier K⟧
⟹  (v x = v y) = (n_val K v x = n_val K v y)"
apply (subst n_val[THEN sym, of v x], assumption+,
subst n_val[THEN sym, of v y], assumption+,
frule Lv_pos[of v], frule Lv_z[of v], erule exE, simp,
frule_tac s = z in zless_neq[THEN not_sym, of "0"])
apply (rule iffI)
apply (rule_tac z = z in amult_eq_eq_r[of _ "n_val K v x" "n_val K v y"],
assumption+)
apply simp
done

lemma (in Corps) val_poss_n_val_poss:"⟦valuation K v; x ∈ carrier K⟧  ⟹
(0 < v x) = (0 < n_val K v x)"
frule val_pos_n_val_pos[of v x], assumption+,
rule iffI, erule conjE, simp,
apply (drule sym,
erule conjE, simp,
frule_tac val_0_n_val_0[THEN sym, of v x], assumption+,
simp)
done

lemma (in Corps) n_val_Pg:"valuation K v ⟹ n_val K v (Pg K v) = 1"
apply (frule val_Pg[of v], simp, (erule conjE)+,
frule n_val[of v "Pg K v"], simp, frule Lv_z[of v], erule exE, simp,
frule Lv_pos[of v], simp, frule_tac i = 0 and j = z in zless_neq)
apply (rotate_tac -1, frule not_sym, thin_tac "0 ≠ z",
subgoal_tac "n_val K v (Pg K v) * ant z = 1 * ant z",
rule_tac z = z in adiv_eq[of _ "n_val K v (Pg K v)" "1"], assumption+,
done

lemma (in Corps) n_val_valuationTr1:"valuation K v ⟹
∀x∈carrier K. n_val K v x ∈ Z⇩∞"
by (rule ballI,
frule n_val[of v], assumption,
frule_tac x = x in value_in_aug_inf[of v], assumption,
frule Lv_z[of v], erule exE, simp,
rule contrapos_pp, simp+)

lemma (in Corps) n_val_t2p:"⟦valuation K v; x ∈ carrier K; y ∈ carrier K⟧ ⟹
n_val K v (x ⋅⇩r y) = n_val K v x + (n_val K v y)"
apply (cut_tac field_is_ring,
frule Ring.ring_tOp_closed[of K x y], assumption+,
frule n_val[of v "x ⋅⇩r y"], assumption+,
frule Lv_pos[of "v"],
frule n_val[THEN sym, of v x], assumption+,
frule n_val[THEN sym, of v y], assumption+, simp,
frule Lv_z[of v], erule exE, simp)
apply (subgoal_tac "ant z ≠ 0")
apply (frule_tac z1 = z in amult_distrib1[THEN sym, of _ "n_val K v x"
"n_val K v y"], simp,
thin_tac "n_val K v x * ant z + n_val K v y * ant z =
(n_val K v x + n_val K v y) * ant z",
rule_tac z = z and a = "n_val K v (x ⋅⇩r y)" and
b = "n_val K v x + n_val K v y" in adiv_eq, simp, assumption+, simp)
done

lemma (in Corps) n_val_valuationTr2:"⟦ valuation K v; x ∈ carrier K;
y ∈ carrier K⟧  ⟹
amin (n_val K v x) (n_val K v y) ≤ (n_val K v ( x ± y))"
apply (frule n_val[THEN sym, of v x], assumption+,
frule n_val[THEN sym, of v y], assumption+,
frule n_val[THEN sym, of v "x ± y"],
cut_tac field_is_ring, frule Ring.ring_is_ag[of "K"],
rule aGroup.ag_pOp_closed, assumption+)
apply (frule amin_le_plus[of v x y], assumption+, simp,
simp add:amult_commute[of _ "Lv K v"],
frule Lv_z[of v], erule exE, simp,
frule Lv_pos[of v], simp,
done

lemma (in Corps) n_val_valuation:"valuation K v ⟹
valuation K (n_val K v)"
apply (cut_tac field_is_ring, frule Ring.ring_is_ag)
apply (frule Lv_z[of v], erule exE, frule Lv_pos[of v], simp,
subst valuation_def)
apply (rule conjI, simp add:n_val_def restrict_def extensional_def)
apply (rule conjI, frule n_val[of v 𝟬],
frule Lv_z[of v], erule exE, frule Lv_pos[of v],
cut_tac mem_ant[of "n_val K v (𝟬)"], erule disjE,
erule disjE, erule exE, simp add:a_z_z value_of_zero, assumption+)
apply (rule conjI, rule ballI,
frule_tac x = x in val_nonzero_noninf[of v], simp+,
apply (rule conjI, (rule ballI)+, simp add:n_val_t2p,
rule conjI, rule ballI, rule impI,
frule Lv_z[of v], erule exE,
frule Lv_pos[of v], simp,
frule_tac x = x in n_val[of v], simp,
frule_tac w1 = z and x1 = 0 and y1 = "n_val K v x" in
frule_tac x = x in val_axiom4[of v], assumption+,
frule_tac x1 = "1⇩r ± x" in n_val[THEN sym, of v],
frule Ring.ring_is_ag[of "K"],
assumption,
frule_tac w = z and x = 0 and y = "n_val K v (1⇩r ± x)"
in amult_pos_mono_r,

apply (frule val_axiom5[of v], erule exE,
(erule conjE)+,
frule_tac x = x in value_n0_n_val_n0[of v], assumption+,
frule_tac x = x in val_noninf_n_val_noninf, simp,
blast)
done

lemma (in Corps) n_val_le_val:"⟦valuation K v; x ∈ carrier K; 0 ≤ (v x)⟧  ⟹
(n_val K v x) ≤(v x)"
by (subst n_val[THEN sym, of v x], assumption+,
frule Lv_pos[of v],
frule Lv_z[of v], erule exE,
cut_tac b = z and x = "n_val K v x" in amult_pos, simp+,

lemma (in Corps) n_val_surj:"valuation K v ⟹
∃x∈ carrier K. n_val K v x = 1"
apply (frule Lv_z[of v], erule exE,
frule Lv_pos[of v],
frule AMin_k[of v], erule bexE, frule_tac x = k in n_val[of v], simp,
apply (subgoal_tac "n_val K v k * ant z = 1 * ant z",
subgoal_tac "z ≠ 0",
frule_tac z = z and a = "n_val K v k" and b = 1 in amult_eq_eq_r,
done

lemma (in Corps) n_value_in_aug_inf:"⟦valuation K v; x ∈ carrier K⟧ ⟹
n_val K v x ∈ Z⇩∞"
by (frule n_val[of v x], assumption,
frule Lv_pos[of v], frule Lv_z[of v], erule exE, simp,
frule value_in_aug_inf[of v x], assumption+, simp add:aug_inf_def)

lemma (in Corps) val_surj_n_valTr:"⟦valuation K v; ∃x ∈ carrier K. v x = 1⟧
⟹  Lv K v = 1"
apply (erule bexE,
frule_tac x = x in n_val[of v],
simp, frule Lv_pos[of v])
apply (frule_tac w = "Lv K v" and x = "n_val K v x" in amult_1_both)
apply simp+
done

lemma (in Corps) val_surj_n_val:"⟦valuation K v; ∃x ∈ carrier K. v x = 1⟧ ⟹
(n_val K v) = v"
apply (rule funcset_eq[of _ "carrier K"],
apply (rule ballI,
frule val_surj_n_valTr[of v], assumption+,
frule_tac x = x in n_val[of v], assumption+,
done

lemma (in Corps) n_val_n_val:"valuation K v ⟹
n_val K (n_val K v)  = n_val K v"
by (frule n_val_valuation[of v],
frule n_val_surj[of v],

lemma nnonzero_annonzero:"0 < N ⟹ an N ≠ 0"
apply (simp only:an_0[THEN sym])
apply (subst aneq_natneq, simp)
done

section "Valuation ring"

definition
Vr :: "[('r, 'm) Ring_scheme, 'r ⇒ ant] ⇒ ('r, 'm) Ring_scheme" where
"Vr K v = Sr K ({x. x ∈ carrier K ∧ 0 ≤ (v x)})"

definition
vp :: "[('r, 'm) Ring_scheme, 'r ⇒ ant] ⇒ 'r set" where
"vp K v = {x. x ∈ carrier (Vr K v) ∧ 0 < (v x)}"

definition
r_apow :: "[('r, 'm) Ring_scheme, 'r set, ant] ⇒ 'r set" where
"r_apow R I a = (if a = ∞ then {𝟬⇘R⇙} else
(if a = 0 then carrier R else I⇗♢R (na a)⇖))"
(** 0 ≤ a and a ≠ -∞ **)

abbreviation
RAPOW  ("(3_⇗ _ _⇖)" [62,62,63]62) where
"I⇗R a⇖ == r_apow R I a"

lemma (in Ring) ring_pow_apow:"ideal R I ⟹
I⇗♢R n⇖ =  I⇗R (an n)⇖"
apply (case_tac "n = 0", simp)
done

lemma (in Ring) r_apow_Suc:"ideal R I ⟹ I⇗R (an (Suc 0))⇖ = I"
apply (simp only:ant_1[THEN sym])
apply (simp del:ant_1 add:z_neq_inf[of 1, THEN not_sym])
done

lemma (in Ring) apow_ring_pow:"ideal R I ⟹
I⇗♢R n⇖ =  I⇗R (an n)⇖"
apply (case_tac "n = 0", simp add:an_0)
cut_tac an_neq_inf[of n],
simp add: less_le[of 0 "an n"] na_an)
done

lemma (in Corps) Vr_ring:"valuation K v ⟹ Ring (Vr K v)"
apply (cut_tac field_is_ring, frule Ring.ring_is_ag[of "K"],
apply (intro conjI subsetI)
apply (simp_all add: value_of_one Ring.ring_one[of "K"])
apply ((rule allI, rule impI)+,
(erule conjE)+, rule conjI, rule aGroup.ag_pOp_closed, assumption+,
rule aGroup.ag_mOp_closed, assumption+)
apply (frule_tac x = x and y = "-⇩a y" in amin_le_plus[of v], assumption+,
rule aGroup.ag_mOp_closed, assumption+,
frule_tac z = 0 and x = "v x" and y = "v y" in amin_ge1, assumption+,
frule_tac i = 0 and j = "amin (v x) (v y)" and k = "v (x ± -⇩a y)" in
ale_trans, assumption+, simp)

lemma (in Corps) val_pos_mem_Vr:"⟦valuation K v; x ∈ carrier K⟧ ⟹
(0 ≤ (v x)) = (x ∈ carrier (Vr K v))"
by (rule iffI, (simp add:Vr_def Sr_def)+)

lemma (in Corps) val_poss_mem_Vr:"⟦valuation K v; x ∈ carrier K; 0 < (v x)⟧
⟹  x ∈ carrier (Vr K v)"
by (frule aless_imp_le[of "0" "v x"], simp add:val_pos_mem_Vr)

lemma (in Corps) Vr_one:"valuation K v ⟹ 1⇩r⇘K⇙ ∈ carrier (Vr K v)"
by (cut_tac field_is_ring, frule Ring.ring_one[of "K"],
frule val_pos_mem_Vr[of v "1⇩r"], assumption+,

lemma (in Corps) Vr_mem_f_mem:"⟦valuation K v; x ∈ carrier (Vr K v)⟧
⟹  x ∈ carrier K"

lemma (in Corps) Vr_0_f_0:"valuation K v ⟹ 𝟬⇘Vr K v⇙ = 𝟬"

lemma (in Corps) Vr_1_f_1:"valuation K v ⟹ 1⇩r⇘(Vr K v)⇙ = 1⇩r"

lemma (in Corps) Vr_pOp_f_pOp:"⟦valuation K v; x ∈ carrier (Vr K v);
y ∈ carrier (Vr K v)⟧ ⟹  x ±⇘Vr K v⇙ y = x ± y"

lemma (in Corps) Vr_mOp_f_mOp:"⟦valuation K v; x ∈ carrier (Vr K v)⟧
⟹ -⇩a⇘(Vr K v)⇙ x = -⇩a x"

lemma (in Corps) Vr_tOp_f_tOp:"⟦valuation K v; x ∈ carrier (Vr K v);
y ∈ carrier(Vr K  v)⟧ ⟹  x ⋅⇩r⇘(Vr K v)⇙ y = x ⋅⇩r y"

lemma (in Corps) Vr_pOp_le:"⟦valuation K v; x ∈ carrier K;
y ∈ carrier (Vr K v)⟧  ⟹ v x ≤ (v x + (v y))"
apply (frule val_pos_mem_Vr[THEN sym, of v y],
done

lemma (in Corps) Vr_integral:"valuation K v ⟹ Idomain (Vr K v)"
rule allI, rule impI, rule allI, (rule impI)+,
apply (rule contrapos_pp, simp+, erule conjE,
cut_tac field_is_idom,
frule_tac x = a in Vr_mem_f_mem[of v], assumption,
frule_tac x = b in Vr_mem_f_mem[of v], assumption,
frule_tac x = a and y = b in Idomain.idom_tOp_nonzeros[of "K"],
assumption+, simp)
done

lemma (in Corps) Vr_exp_mem:"⟦valuation K v; x ∈ carrier (Vr K v)⟧
⟹  x^⇗K n⇖ ∈ carrier (Vr K v)"
by (frule Vr_ring[of v],

lemma (in Corps) Vr_exp_f_exp:"⟦valuation K v; x ∈ carrier (Vr K v)⟧ ⟹
x^⇗(Vr K v) n⇖ =  x^⇗K n⇖"
apply (induct_tac n,
thin_tac "x^⇗(Vr K v) n⇖ = x^⇗K n⇖")
apply (rule Vr_tOp_f_tOp, assumption+,
done

lemma (in Corps) Vr_potent_nonzero:"⟦valuation K v;
x ∈ carrier (Vr K v) - {𝟬⇘Vr K v⇙}⟧  ⟹ x^⇗K n⇖ ≠ 𝟬⇘Vr K v⇙"
apply (frule Vr_mem_f_mem[of v x], simp,
apply (frule Vr_mem_f_mem[of v x], assumption+,
done

lemma (in Corps) elem_0_val_if:"⟦valuation K v; x ∈ carrier K; v x = 0⟧
⟹ x ∈ carrier (Vr K v) ∧ x⇗‐ K⇖ ∈ carrier (Vr K v)"
apply (frule val_pos_mem_Vr[of v x], assumption, simp)
apply (frule value_zero_nonzero[of "v" "x"], simp add:Vr_mem_f_mem, simp)
apply (frule value_of_inv[of v x], assumption+,
simp, subst val_pos_mem_Vr[THEN sym, of v "x⇗‐K⇖"], assumption+,
cut_tac invf_closed[of x], simp+)
done

lemma (in Corps) elem0val:"⟦valuation K v; x ∈ carrier K; x ≠ 𝟬⟧ ⟹
(v x = 0) = ( x ∈ carrier (Vr K v) ∧ x⇗‐ K⇖ ∈ carrier (Vr K v))"
apply (rule iffI, rule elem_0_val_if[of v], assumption+,
erule conjE)
apply (simp add:val_pos_mem_Vr[THEN sym, of v x],
frule Vr_mem_f_mem[of v "x⇗‐K⇖"], assumption+,
simp add:val_pos_mem_Vr[THEN sym, of v "x⇗‐K⇖"],
simp add:value_of_inv, frule ale_minus[of "0" "- v x"],
done

lemma (in Corps) ideal_inc_elem0val_whole:"⟦ valuation K v; x ∈ carrier K;
v x = 0; ideal (Vr K v) I; x ∈ I⟧ ⟹  I = carrier (Vr K v)"
apply (frule elem_0_val_if[of v x], assumption+, erule conjE,
frule value_zero_nonzero[of v x], assumption+,
frule Vr_ring[of v],
frule_tac I = I and x = x and r = "x⇗‐K⇖" in
Ring.ideal_ring_multiple[of "Vr K v"], assumption+,
cut_tac invf_closed1[of x], simp+, (erule conjE)+)
apply (simp add:Vr_tOp_f_tOp, cut_tac invf_inv[of x], simp+,
simp add: Vr_1_f_1[THEN sym, of v],
done

lemma (in Corps) vp_mem_Vr_mem:"⟦valuation K v; x ∈ (vp K v)⟧ ⟹
x ∈ carrier (Vr K v)"
by (rule val_poss_mem_Vr[of v x], assumption+, (simp add:vp_def
Vr_def Sr_def)+)

lemma (in Corps) vp_mem_val_poss:"⟦ valuation K v; x ∈ carrier K⟧ ⟹
(x ∈ vp K v) = (0 < (v x))"

lemma (in Corps) Pg_in_Vr:"valuation K v ⟹  Pg K v ∈ carrier (Vr K v)"
by (frule val_Pg[of v], erule conjE,
frule Lv_pos[of v], drule sym,
simp, erule conjE,

lemma (in Corps) vp_ideal:"valuation K v ⟹  ideal (Vr K v) (vp K v)"
apply (cut_tac field_is_ring,
frule Vr_ring[of v],
rule Ring.ideal_condition1, assumption+,
apply (frule val_Pg[of v],
frule Lv_pos[of v], simp, (erule conjE)+,
drule sym, simp,
frule val_poss_mem_Vr[of v "Pg K v"], assumption+, blast)

apply ((rule ballI)+,
frule_tac x = x in vp_mem_Vr_mem[of v], assumption) apply (
frule_tac x = y in vp_mem_Vr_mem[of v], assumption,
frule Ring.ring_is_ag[of "Vr K v"],
frule_tac x = x and y = y in aGroup.ag_pOp_closed, assumption+, simp)
cut_tac x = "v x" and y = "v y" in amin_le_l,
frule_tac x = x and y = y in amin_le_plus,
(frule_tac z = 0 and x = "v x" and y = "v y" in amin_gt, assumption+),
rule_tac x = 0 and y = "amin (v x) (v y)" and z = "v (x ± y)" in
less_le_trans, assumption+)
apply ((rule ballI)+,
frule_tac x1 = r in val_pos_mem_Vr[THEN sym, of v],
frule_tac x = x in vp_mem_Vr_mem[of v], simp add:Vr_pOp_f_pOp,
apply (frule_tac x = r in Vr_mem_f_mem[of v], assumption+,
frule_tac x = x in Vr_mem_f_mem[of v], assumption+,
done

lemma (in Corps) vp_not_whole:"valuation K v ⟹
(vp K v) ≠ carrier (Vr K v)"
apply (cut_tac field_is_ring, frule Ring.ring_is_ag[of "K"],
frule Vr_ring[of v])
apply (rule contrapos_pp, simp+,
drule sym,
frule Ring.ring_one[of "Vr K v"], simp,
frule Ring.ring_one[of "K"])
apply (simp only:vp_mem_val_poss[of v "1⇩r"],
done

lemma (in Ring) elem_out_ideal_nonzero:"⟦ideal R I; x ∈ carrier R;
x ∉ I⟧ ⟹ x ≠ 𝟬⇘R⇙"
by (rule contrapos_pp, simp+, frule ideal_zero[of I],
simp)

lemma (in Corps) vp_prime:"valuation K v ⟹ prime_ideal (Vr K v) (vp K v)"
apply (rule conjI)
(** if the unit is contained in (vp K v), then (vp K v) is
the whole ideal, this contradicts vp_not_whole **)
apply (rule contrapos_pp, simp+,
frule Vr_ring[of v],
frule vp_ideal[of v],
frule Ring.ideal_inc_one[of "Vr K v" "vp K v"], assumption+,

(** if x ⋅⇘(Vr K v)⇙ y is in (vp K v), then 0 < v (x ⋅⇩K y). We have
0 ≤ (v x) and 0 ≤ (v y), because x and y are elements of Vr K v.
Since v (x ⋅⇩K y) = (v x) + (v y), we have 0 < (v x) or 0 < (v y).
To obtain the final conclusion, we suppose ¬ (x ∈ vp K v ∨ y ∈ vp K v)
then, we have (v x) = 0 and (v y) = 0. Frome this, we have v (x ⋅⇩K y) =
apply ((rule ballI)+, rule impI, rule contrapos_pp, simp+, (erule conjE)+,
frule Vr_ring[of v]) apply (
frule_tac x = x in Vr_mem_f_mem[of v], assumption) apply (
frule_tac x = y in Vr_mem_f_mem[of v], assumption) apply (
frule vp_ideal[of v],
frule_tac x = x in Ring.elem_out_ideal_nonzero[of "Vr K v" "vp K v"],
assumption+) apply (
frule_tac x = y in Ring.elem_out_ideal_nonzero[of "Vr K v" "vp K v"],
frule_tac x = "x ⋅⇩r y" in vp_mem_val_poss[of v],
apply (cut_tac field_is_ring,
frule_tac x = x and y = y in Ring.ring_tOp_closed, assumption+,
frule_tac x1 = x in val_pos_mem_Vr[THEN sym, of v], assumption+,
frule_tac x1 = y in val_pos_mem_Vr[THEN sym, of v], assumption+,
frule_tac P = "x ∈ carrier (Vr K v)" and Q = "0 ≤ v x" in eq_prop,
assumption,
frule_tac P = "y ∈ carrier (Vr K v)" and Q = "0 ≤ v y" in eq_prop,
assumption,
frule_tac x = "v x" and y = 0 in ale_antisym, assumption+,
frule_tac x = "v y" and y = 0 in ale_antisym, assumption+,
done

lemma (in Corps) vp_pow_ideal:"valuation K v ⟹
ideal (Vr K v) ((vp K v)⇗♢(Vr K v) n⇖)"
by (frule Vr_ring[of v], frule vp_ideal[of v],

lemma (in Corps) vp_apow_ideal:"⟦valuation K v; 0 ≤ n⟧ ⟹
ideal (Vr K v) ((vp K v)⇗(Vr K v) n⇖)"
apply (frule Vr_ring[of v])
apply (case_tac "n = 0",
apply (case_tac "n = ∞",
done

lemma (in Corps) mem_vp_apow_mem_Vr:"⟦valuation K v;
0 ≤ N; x ∈ vp K v ⇗(Vr K v) N⇖⟧  ⟹ x ∈ carrier (Vr K v)"
by (frule Vr_ring[of v], frule vp_apow_ideal[of v N], assumption,

lemma (in Corps) elem_out_vp_unit:"⟦valuation K v; x ∈ carrier (Vr K v);
x ∉ vp K v⟧  ⟹ v x = 0"
by (metis Vr_mem_f_mem ale_antisym aneg_le val_pos_mem_Vr vp_mem_val_poss)

lemma (in Corps) vp_maximal:"valuation K v ⟹
maximal_ideal (Vr K v) (vp K v)"
apply (frule Vr_ring[of v],
(** we know that vp is not a whole ideal, and so vp does not include 1 **)
apply (frule vp_not_whole[of v],
rule conjI, rule contrapos_pp, simp+, frule vp_ideal[of v],
frule Ring.ideal_inc_one[of "Vr K v" "vp K v"], assumption+)
apply simp
(** onemore condition of maximal ideal **)
apply (rule equalityI,
rule subsetI, simp, erule conjE,
case_tac "x = vp K v", simp, simp, rename_tac X)
(** show exists a unit contained in X **)
apply (frule_tac A = X in sets_not_eq[of _ "vp K v"], assumption+,
erule bexE,
frule_tac I = X and h = a in Ring.ideal_subset[of "Vr K v"],
assumption+,
frule_tac x = a in elem_out_vp_unit[of v], assumption+)
(** since v a = 0, we see a is a unit **)
apply (frule_tac x = a and I = X in ideal_inc_elem0val_whole [of v],

apply (rule subsetI, simp, erule disjE,
done

lemma (in Corps) ideal_sub_vp:"⟦ valuation K v; ideal (Vr K v) I;
I ≠ carrier (Vr K v)⟧ ⟹ I ⊆ (vp K v)"
apply (frule Vr_ring[of v], rule contrapos_pp, simp+)
erule bexE)
apply (frule_tac h = x in Ring.ideal_subset[of "Vr K v" I], assumption+,
frule_tac x = x in elem_out_vp_unit[of v], assumption+,
frule_tac x = x in ideal_inc_elem0val_whole[of v _ I],
done

lemma (in Corps) Vr_local:"⟦valuation K v; maximal_ideal (Vr K v) I⟧ ⟹
(vp K v) = I"
apply (frule Vr_ring[of v],
frule ideal_sub_vp[of v I], simp add:Ring.maximal_ideal_ideal)
frule conjunct2, fold maximal_ideal_def, frule conjunct1,
apply (rule equalityI) prefer 2 apply assumption
apply (rule contrapos_pp, simp+,
frule sets_not_eq[of "vp K v" I], assumption+, erule bexE)
apply (frule_tac x = a in vp_mem_Vr_mem[of v],
frule Ring.maximal_ideal_ideal[of "Vr K v" "I"], assumption,
frule_tac x = a in Ring.elem_out_ideal_nonzero[of "Vr K v" "I"],
assumption+,
frule vp_ideal[of v], rule Ring.ideal_subset[of "Vr K v" "vp K v"],
assumption+)

apply (frule_tac a = a in Ring.principal_ideal[of "Vr K v"], assumption+,
frule Ring.maximal_ideal_ideal[of "Vr K v" I], assumption+,
frule_tac ?I2.0 = "Vr K v ♢⇩p a"in Ring.sum_ideals[of "Vr K v" "I"],
frule_tac ?I2.0 = "Vr K v ♢⇩p a"in Ring.sum_ideals_la1[of "Vr K v" "I"],
assumption+,
frule_tac ?I2.0 = "Vr K v ♢⇩p a"in Ring.sum_ideals_la2[of "Vr K v" "I"],
assumption+,
frule_tac a = a in Ring.a_in_principal[of "Vr K v"], assumption+,
frule_tac A = "Vr K v ♢⇩p a" and B = "I ∓⇘(Vr K v)⇙ (Vr K v ♢⇩p a)"
and c = a in subsetD, assumption+)
thm Ring.sum_ideals_cont[of "Vr K v" "vp K v" I ]
apply (frule_tac B = "Vr K v ♢⇩p a" in Ring.sum_ideals_cont[of "Vr K v"
"vp K v" I], simp add:vp_ideal, assumption)
apply (frule_tac a = a in Ring.ideal_cont_Rxa[of "Vr K v" "vp K v"],
subgoal_tac "I ∓⇘(Vr K v)⇙ (Vr K v ♢⇩p a) ∈ {J. ideal (Vr K v) J ∧ I ⊆ J}",
simp, thin_tac "{J. ideal (Vr K v) J ∧ I ⊆ J} = {I, carrier (Vr K v)}")
apply (erule disjE, simp)
apply (cut_tac A = "carrier (Vr K v)" and B = "I ∓⇘Vr K v⇙ Vr K v ♢⇩p a" and
C = "vp K v" in subset_trans, simp, assumption,
frule Ring.ideal_subset1[of "Vr K v" "vp K v"], simp add:vp_ideal,
frule equalityI[of "vp K v" "carrier (Vr K v)"], assumption+,
frule vp_not_whole[of v], simp)
apply blast
done

lemma (in Corps) v_residue_field:"valuation K v ⟹
Corps ((Vr K v)  /⇩r (vp K v))"
by (frule Vr_ring[of v],
rule Ring.residue_field_cd [of "Vr K v" "vp K v"], assumption+,

lemma (in Corps) Vr_n_val_Vr:"valuation K v ⟹
carrier (Vr K v) = carrier (Vr K (n_val K v))"
rule equalityI,
(rule subsetI, simp, erule conjE, simp add:val_pos_n_val_pos),
(rule subsetI, simp, erule conjE, simp add:val_pos_n_val_pos[THEN sym]))

section "Ideals in a valuation ring"

lemma (in Corps) Vr_has_poss_elem:"valuation K v ⟹
∃x∈carrier (Vr K v) - {𝟬⇘Vr K v⇙}. 0 < v x"
apply (frule val_Pg[of v], erule conjE,
frule Lv_pos[of v], drule sym,
subst Vr_0_f_0, assumption+)
apply (frule aeq_ale[of "Lv K v" "v (Pg K v)"],
frule aless_le_trans[of "0" "Lv K v" "v (Pg K v)"], assumption+,
frule val_poss_mem_Vr[of v "Pg K v"],
simp, assumption, blast)
done

lemma (in Corps) vp_nonzero:"valuation K v ⟹  vp K v ≠  {𝟬⇘Vr K v⇙}"
apply (frule Vr_has_poss_elem[of v], erule bexE,
simp, erule conjE,
frule_tac x1 = x in vp_mem_val_poss[THEN sym, of v],
simp add:Vr_mem_f_mem, simp, rule contrapos_pp, simp+)
done

lemma (in Corps) field_frac_mul:"⟦x ∈ carrier K; y ∈ carrier K; y ≠ 𝟬⟧
⟹   x = (x ⋅⇩r  (y⇗‐K⇖)) ⋅⇩r y"
apply (cut_tac invf_closed[of y],
cut_tac field_is_ring,
subst linvf[of y], simp, simp add:Ring.ring_r_one[of K], simp)
done

lemma (in Corps) elems_le_val:"⟦valuation K v; x ∈ carrier K; y ∈ carrier K;
x ≠ 𝟬; v x ≤ (v y)⟧  ⟹ ∃r∈carrier (Vr K v). y = r ⋅⇩r x"
apply (frule ale_diff_pos[of "v x" "v y"], simp add:diff_ant_def,
simp add:value_of_inv[THEN sym, of v x],
cut_tac invf_closed[of "x"],
simp only:val_t2p[THEN sym, of v y "x⇗‐K⇖"])
apply (cut_tac field_is_ring,
frule_tac x = y and y = "x⇗‐K⇖" in Ring.ring_tOp_closed[of "K"],
assumption+,
simp add:val_pos_mem_Vr[of v "y ⋅⇩r (x⇗‐K⇖)"],
frule field_frac_mul[of y x], assumption+, blast)
apply simp
done

lemma (in Corps) val_Rxa_gt_a:"⟦valuation K v; x ∈ carrier (Vr K v) - {𝟬};
y ∈ carrier (Vr K v);  y ∈ Rxa (Vr K v) x⟧ ⟹ v x ≤ (v y)"
erule bexE,
frule_tac x = r in Vr_mem_f_mem[of v], assumption+,
frule_tac x = x in Vr_mem_f_mem[of v], assumption+)
apply (subst val_t2p, assumption+,
frule_tac y = "v r" in aadd_le_mono[of "0" _ "v x"],
done

lemma (in Corps) val_Rxa_gt_a_1:"⟦valuation K v; x ∈ carrier (Vr K v);
y ∈ carrier (Vr K v); x ≠ 𝟬; v x ≤ (v y)⟧ ⟹ y ∈ Rxa (Vr K v) x"
apply (frule_tac x = x in Vr_mem_f_mem[of v], assumption+,
frule_tac x = y in Vr_mem_f_mem[of v], assumption+,
frule v_ale_diff[of v x y], assumption+,
cut_tac invf_closed[of x],
cut_tac field_is_ring, frule Ring.ring_tOp_closed[of K y "x⇗‐K⇖"],
assumption+)
apply (simp add:val_pos_mem_Vr[of "v" "y ⋅⇩r (x⇗‐K⇖)"],
frule field_frac_mul[of "y" "x"], assumption+,
done

lemma (in Corps) eqval_inv:"⟦valuation K v; x ∈ carrier K; y ∈ carrier K;
y ≠ 𝟬; v x = v y⟧ ⟹  0 = v (x ⋅⇩r (y⇗‐K⇖))"
by (cut_tac invf_closed[of y],
simp)

lemma (in Corps) eq_val_eq_idealTr:"⟦valuation K v;
x ∈ carrier (Vr K v) - {𝟬}; y ∈ carrier  (Vr K v); v x ≤ (v y)⟧ ⟹
Rxa (Vr K v) y ⊆  Rxa (Vr K v) x"
apply (frule val_Rxa_gt_a_1[of v x y], simp+,
erule conjE)
apply (frule_tac x = x in Vr_mem_f_mem[of v], assumption+,
frule Vr_ring[of v],
frule Ring.principal_ideal[of "Vr K v" "x"], assumption,
frule Ring.ideal_cont_Rxa[of "Vr K v" "(Vr K v) ♢⇩p x" "y"],
assumption+)
done

lemma (in Corps) eq_val_eq_ideal:"⟦valuation K v;
x ∈ carrier (Vr K v); y ∈ carrier  (Vr K v); v x = v y⟧
⟹ Rxa (Vr K v) x = Rxa (Vr K v) y"
apply (case_tac "x = 𝟬⇘K⇙",
frule value_inf_zero[of v y],
simp add:Vr_mem_f_mem, rule sym, assumption, simp)
apply (rule equalityI,
rule eq_val_eq_idealTr[of v y x], assumption+,
drule sym, simp,
frule Vr_mem_f_mem[of v x], assumption+,
frule value_inf_zero[of v x], assumption+,
rule sym, assumption, simp, simp, simp)
apply (rule eq_val_eq_idealTr[of v x y], assumption+, simp,
assumption, rule aeq_ale, assumption+)
done

lemma (in Corps) eq_ideal_eq_val:"⟦valuation K v; x ∈ carrier (Vr K v);
y ∈ carrier (Vr K v); Rxa (Vr K v) x = Rxa (Vr K v) y⟧  ⟹ v x = v y"
apply (case_tac "x = 𝟬⇘K⇙", simp,
drule sym,
frule Vr_ring[of v],
frule Ring.a_in_principal[of "Vr K v" y], assumption+, simp,
thin_tac "Vr K v ♢⇩p y = Vr K v ♢⇩p (𝟬)", simp add:Rxa_def,
erule bexE, simp add:Vr_0_f_0[of v, THEN sym])
frule_tac x = r in Vr_mem_f_mem[of v], assumption+,
apply (frule Vr_ring[of v],
frule val_Rxa_gt_a[of v x y], simp,
simp)
apply (drule sym,
frule Ring.a_in_principal[of "Vr K v" "y"], simp, simp)
apply (frule val_Rxa_gt_a[of v y x],
simp, rule contrapos_pp, simp+,
frule Ring.a_in_principal[of "Vr K v" "x"], assumption+,
erule bexE, simp add:Vr_tOp_f_tOp, cut_tac field_is_ring,
frule_tac x = r in Vr_mem_f_mem[of v], assumption+,
frule Ring.a_in_principal[of "Vr K v" "x"], assumption+, simp,
rule ale_antisym, assumption+)
done

lemma (in Corps) zero_val_gen_whole:
"⟦valuation K v; x ∈ carrier (Vr K v)⟧ ⟹
(v x = 0) = (Rxa (Vr K v) x = carrier (Vr K v))"
apply (frule Vr_mem_f_mem[of v x], assumption,
frule Vr_ring[of v])
apply (rule iffI,
frule Ring.principal_ideal[of "Vr K v" "x"], assumption+,
frule Ring.a_in_principal[of "Vr K v" "x"], assumption+,
rule ideal_inc_elem0val_whole[of v x "Vr K v ♢⇩p x"], assumption+,
frule Ring.ring_one[of "Vr K v"],
frule eq_set_inc[of "1⇩r⇘(Vr K v)⇙"
"carrier (Vr K v)" "Vr K v ♢⇩p x"], drule sym, assumption,
thin_tac "1⇩r⇘(Vr K v)⇙ ∈ carrier (Vr K v)",
thin_tac "Vr K v ♢⇩p x = carrier (Vr K v)")
frule value_of_one[of v], simp,
frule_tac x = r in Vr_mem_f_mem[of v], assumption+,
rule contrapos_pp, simp+,
cut_tac less_le[THEN sym, of "0" "v x"], drule not_sym, simp,
frule_tac x = "v r" and y = "v x" in aadd_pos_poss, assumption+,
simp)
done

lemma (in Corps) elem_nonzeroval_gen_proper:"⟦ valuation K v;
x ∈ carrier (Vr K v); v x ≠ 0⟧ ⟹ Rxa (Vr K v) x ≠ carrier (Vr K v)"
apply (rule contrapos_pp, simp+)
done

text‹We prove that Vr K v is a principal ideal ring›

definition
LI :: "[('r, 'm) Ring_scheme, 'r ⇒ ant, 'r set] ⇒ ant" where
(** The least nonzero value of I **)
"LI K v I = AMin (v ` I)"

definition
Ig :: "[('r, 'm) Ring_scheme, 'r ⇒ ant, 'r set] ⇒ 'r" where
(** Generator of I **)
"Ig K v I = (SOME x. x ∈ I ∧ v x = LI K v I)"

lemma (in Corps) val_in_image:"⟦valuation K v; ideal (Vr K v) I; x ∈ I⟧ ⟹
v x ∈ v ` I"

lemma (in Corps) I_vals_nonempty:"⟦valuation K v; ideal (Vr K v) I⟧ ⟹
v ` I ≠ {}"
by (frule Vr_ring[of v],
frule Ring.ideal_zero[of "Vr K v" "I"],
assumption+, rule contrapos_pp, simp+)

lemma (in Corps) I_vals_LBset:"⟦ valuation K v; ideal (Vr K v) I⟧ ⟹
v ` I  ⊆ LBset 0"
apply (frule Vr_ring[of v],
apply (erule bexE,
frule_tac h = xa in Ring.ideal_subset[of "Vr K v" "I"], assumption+)
apply (frule_tac x1 = xa in val_pos_mem_Vr[THEN sym, of v],
done

lemma (in Corps) LI_pos:"⟦valuation K v; ideal (Vr K v) I⟧ ⟹ 0 ≤ LI K v I"
frule I_vals_LBset[of v],
frule I_vals_nonempty[of v], simp only:ant_0)

apply (simp only:ant_0[THEN sym], frule AMin[of "v ` I" "0"], assumption,
erule conjE, frule subsetD[of "v ` I" "LBset (ant 0)" "AMin (v ` I)"],
done

lemma (in Corps) LI_poss:"⟦valuation K v; ideal (Vr K v) I;
I ≠ carrier (Vr K v)⟧ ⟹ 0 < LI K v I"
apply (subst less_le)
apply (rule contrapos_pp, simp+)

frule I_vals_LBset[of v], assumption+,
frule I_vals_nonempty[of v], assumption+, simp only:ant_0)

apply (simp only:ant_0[THEN sym], frule AMin[of "v ` I" "0"], assumption,
erule conjE, frule subsetD[of "v ` I" "LBset (ant 0)" "AMin (v ` I)"],

apply (thin_tac "∀x∈I. ant 0 ≤ v x",
thin_tac "v ` I ⊆ {x. ant 0 ≤ x}", simp add:image_def,
apply (frule Vr_ring[of v],
frule_tac h = x in Ring.ideal_subset[of "Vr K v" "I"], assumption+,
frule_tac x = x in zero_val_gen_whole[of v], assumption+,
simp,
frule_tac a = x in Ring.ideal_cont_Rxa[of "Vr K v" "I"], assumption+,
simp, frule Ring.ideal_subset1[of "Vr K v" "I"], assumption+)
apply (frule equalityI[of "I" "carrier (Vr K v)"], assumption+, simp)
done

lemma (in Corps) LI_z:"⟦valuation K v; ideal (Vr K v) I; I ≠ {𝟬⇘Vr K v⇙}⟧ ⟹
∃z. LI K v I = ant z"
apply (frule Vr_ring[of v],
frule Ring.ideal_zero[of "Vr K v" "I"], assumption+,
cut_tac mem_ant[of "LI K v I"],
frule LI_pos[of v I], assumption,
erule disjE, simp,
cut_tac minf_le_any[of "0"],
frule ale_antisym[of "0" "-∞"], assumption+, simp)
apply (erule disjE, simp,
frule singleton_sub[of "𝟬⇘Vr K v⇙" "I"],
frule sets_not_eq[of "I" "{𝟬⇘Vr K v⇙}"], assumption+,
erule bexE, simp)

frule I_vals_LBset[of v], assumption+,
simp only:ant_0[THEN sym],
frule I_vals_nonempty[of v], assumption+,
frule AMin[of "v ` I" "0"], assumption, erule conjE)
apply (frule_tac x = a in val_in_image[of v I], assumption+,
drule_tac x = "v a" in bspec, simp,
frule_tac x = a in val_nonzero_z[of v],
erule exE, simp,
cut_tac x = "ant z" in inf_ge_any, frule_tac x = "ant z" in
ale_antisym[of _ "∞"], assumption+, simp)
done

lemma (in Corps) LI_k:"⟦valuation K v; ideal (Vr K v) I⟧ ⟹
∃k∈ I. LI K v I = v k"
frule I_vals_LBset[of v], assumption+,
simp only:ant_0[THEN sym],
frule I_vals_nonempty[of v], assumption+,
frule AMin[of "v ` I" "0"], assumption, erule conjE,
thin_tac "∀x∈v ` I. AMin (v ` I) ≤ x", simp add:image_def)

lemma (in Corps) LI_infinity:"⟦valuation K v; ideal (Vr K v) I⟧ ⟹
(LI K v I = ∞)  = (I = {𝟬⇘Vr K v⇙})"
apply (frule Vr_ring[of v])
apply (rule iffI)
apply (rule contrapos_pp, simp+,
frule Ring.ideal_zero[of "Vr K v" "I"], assumption+,
frule singleton_sub[of "𝟬⇘Vr K v⇙" "I"],
frule sets_not_eq[of "I" "{𝟬⇘Vr K v⇙}"], assumption+,
erule bexE,
frule_tac h = a in Ring.ideal_subset[of "Vr K v" "I"], assumption+,
frule_tac x = a in Vr_mem_f_mem[of v], assumption+,
frule_tac x = a in val_nonzero_z[of v], assumption+,
erule exE,
frule I_vals_LBset[of v], assumption+,
simp only:ant_0[THEN sym],
frule I_vals_nonempty[of v], assumption+,
frule AMin[of "v ` I" "0"], assumption, erule conjE)
apply (frule_tac h = a in Ring.ideal_subset[of "Vr K v" "I"], assumption+,
frule_tac x = a in val_in_image[of v I], assumption+,
drule_tac x = "v a" in bspec, simp)
apply (frule_tac x = a in val_nonzero_z[of v], assumption+,
erule exE, simp,
cut_tac x = "ant z" in inf_ge_any, frule_tac x = "ant z" in
ale_antisym[of _ "∞"], assumption+, simp)

apply (frule sym, thin_tac "I = {𝟬⇘Vr K v⇙}",
frule I_vals_LBset[of v], assumption+,
simp only:ant_0[THEN sym],
frule I_vals_nonempty[of v], assumption+,
frule AMin[of "v ` I" "0"], assumption, erule conjE,
drule sym, simp,
done

lemma (in Corps) val_Ig:"⟦valuation K v; ideal (Vr K v) I⟧ ⟹
(Ig K v I) ∈ I ∧ v (Ig K v I) = LI K v I"
frule LI_k[of v I], assumption+, erule bexE,
drule sym, blast, assumption)

lemma (in Corps) Ig_nonzero:"⟦valuation K v; ideal (Vr K v) I; I ≠ {𝟬⇘Vr K v⇙}⟧
⟹ (Ig K v I) ≠ 𝟬"
by (rule contrapos_pp, simp+,
frule LI_infinity[of v I], assumption+,
frule val_Ig[of v I], assumption+, erule conjE,

lemma (in Corps) Vr_ideal_npowf_closed:"⟦valuation K v; ideal (Vr K v) I;
x ∈ I; 0 < n⟧ ⟹ x⇘K⇙⇗n⇖ ∈ I"
by (simp add:npowf_def, frule Vr_ring[of v],
frule Ring.ideal_npow_closed[of "Vr K v" "I" "x" "nat n"], assumption+,
simp, frule Ring.ideal_subset[of "Vr K v" "I" "x"], assumption+,

lemma (in Corps) Ig_generate_I:"⟦valuation K v; ideal (Vr K v) I⟧ ⟹
(Vr K v) ♢⇩p (Ig K v I) = I"
apply (frule Vr_ring[of v])
apply (case_tac "I = carrier (Vr K v)",
frule sym, thin_tac "I = carrier (Vr K v)",
frule Ring.ring_one[of "Vr K v"],
frule val_Ig[of v I], assumption+, erule conjE,
frule LI_pos[of v I], assumption+,

simp add: LI_def cong del: image_cong_simp,
frule I_vals_LBset[of v], assumption+,
simp only: ant_0[THEN sym],
frule I_vals_nonempty[of v], assumption+,
frule AMin[of "v ` I" "0"], assumption, erule conjE,

frule val_in_image[of v I "1⇩r"], assumption+,
drule_tac x = "v (1⇩r)" in bspec, assumption+,
simp add: value_of_one ant_0 cong del: image_cong_simp,
simp add: zero_val_gen_whole[of v "Ig K v I"])

apply (frule val_Ig[of v I], assumption+, (erule conjE)+,
frule Ring.ideal_cont_Rxa[of "Vr K v" "I" "Ig K v I"], assumption+,
rule equalityI, assumption+)

apply (case_tac "LI K v I = ∞",
frule LI_infinity[of v I], simp,
frule Ring.ring_zero, blast)

apply (rule subsetI,
case_tac "v x = 0",
frule_tac x = x in Vr_mem_f_mem[of v],
frule_tac x = x in zero_val_gen_whole[of v],
frule_tac a = x in Ring.ideal_cont_Rxa[of "Vr K v" "I"], assumption+,
simp, frule Ring.ideal_subset1[of "Vr K v" "I"], assumption,
frule equalityI[of "I" "carrier (Vr K v)"], assumption+, simp)
frule I_vals_LBset[of v], assumption+,
simp only:ant_0[THEN sym],
frule I_vals_nonempty[of v], assumption+,
frule AMin[of "v ` I" "0"], assumption, erule conjE,
frule_tac x = "v x" in bspec,
frule_tac x = x in val_in_image[of v I], assumption+,
simp)
apply (drule_tac x =  x in bspec, assumption,
frule_tac y = x in eq_val_eq_idealTr[of v "Ig K v I"],

apply (frule_tac a = x in Ring.a_in_principal[of "Vr K v"],
done

lemma (in Corps) Pg_gen_vp:"valuation K v  ⟹
(Vr K v) ♢⇩p (Pg K v) = vp K v"
apply (frule vp_ideal[of v],
frule Ig_generate_I[of v "vp K v"], assumption+,
frule vp_not_whole[of v],
frule eq_val_eq_ideal[of v "Ig K v (vp K v)" "Pg K v"],
frule val_Ig [of v "vp K v"], assumption+, erule conjE,

apply (frule val_Pg[of v], erule conjE,
frule Lv_pos[of v],
rotate_tac -2, drule sym, simp,

apply (thin_tac "Vr K v ♢⇩p Ig K v (vp K v) = vp K v",
frule val_Pg[of v], erule conjE,
simp, frule val_Ig[of v "vp K v"], assumption+, erule conjE,
simp, thin_tac "v (Pg K v) = Lv K v",
thin_tac "Ig K v (vp K v) ∈ vp K v ∧ v (Ig K v (vp K v)) =
LI K v (vp K v)", simp add:LI_def Lv_def,
subgoal_tac "v ` vp K v = {x. x ∈ v ` carrier K ∧ 0 < x}",
simp)

apply (thin_tac "ideal (Vr K v) (vp K v)", thin_tac "Pg K v ∈ carrier K",
thin_tac "Pg K v ≠ 𝟬",
rule equalityI, rule subsetI,
simp add:image_def vp_def, erule exE, erule conjE,
(erule conjE)+,
frule_tac x = xa in Vr_mem_f_mem[of v], assumption+, simp, blast)

apply (rule subsetI, simp add:image_def vp_def, erule conjE, erule bexE, simp,
frule_tac x = xa in val_poss_mem_Vr[of v], assumption+,
cut_tac y = "v xa" in less_le[of "0"], simp, blast, simp)
done

lemma (in Corps) vp_gen_t:"valuation K v  ⟹
∃t∈carrier (Vr K v). vp K v = (Vr K v) ♢⇩p t"
by (frule Pg_gen_vp[of v], frule Pg_in_Vr[of v], blast)

lemma (in Corps) vp_gen_nonzero:"⟦valuation K v; vp K v = (Vr K v) ♢⇩p t⟧ ⟹
t ≠ 𝟬⇘Vr K v⇙"
apply (rule contrapos_pp, simp+,
cut_tac Ring.Rxa_zero[of "Vr K v"], drule sym, simp,
done

lemma (in Corps) n_value_idealTr:"⟦valuation K v; 0 ≤ n⟧ ⟹
(vp K v) ⇗♢(Vr K v) n⇖ = Vr K v ♢⇩p ((Pg K v)^⇗(Vr K v) n⇖)"
apply (frule Vr_ring[of v],
frule Pg_gen_vp[THEN sym, of v],
frule val_Pg[of v], simp, (erule conjE)+)
apply (subst Ring.principal_ideal_n_pow[of "Vr K v" "Pg K v"
"Vr K v ♢⇩p Pg K v"], assumption+,
frule Lv_pos[of v], rotate_tac -2, frule sym,
thin_tac "v (Pg K v) = Lv K v", simp, simp add:val_poss_mem_Vr,
simp+)
done

lemma (in Corps) ideal_pow_vp:"⟦valuation K v; ideal (Vr K v) I;
I ≠ carrier (Vr K v); I ≠ {𝟬⇘Vr K v⇙}⟧  ⟹
I = (vp K v)⇗♢ (Vr K v) (na (n_val K v (Ig K v I)))⇖"
apply (frule Vr_ring[of v],
frule Ig_generate_I[of v I], assumption+)

apply (frule n_val[of v "Ig K v I"],
frule val_Ig[of v I], assumption+, erule conjE,
simp add:Ring.ideal_subset[of "Vr K v" "I" "Ig K v I"] Vr_mem_f_mem)

apply (frule val_Pg[of v], erule conjE,
rotate_tac -1, drule sym, simp,
frule Ig_nonzero[of v I], assumption+,
frule LI_pos[of v I], assumption+,
frule Lv_pos[of v],
frule val_Ig[of v I], assumption+, (erule conjE)+,
rotate_tac -1, drule sym, simp,
frule val_pos_n_val_pos[of v "Ig K v I"],
simp)
apply (frule zero_val_gen_whole[THEN sym, of v "Ig K v I"],
simp, rotate_tac -1, drule not_sym,
cut_tac less_le[THEN sym, of "0" "v (Ig K v I)"], simp,
thin_tac "0 ≤ v (Ig K v I)",
frule Ring.ideal_subset[of "Vr K v" I "Ig K v I"], assumption+,
frule Vr_mem_f_mem[of v "Ig K v I"], assumption+,
frule val_poss_n_val_poss[of v "Ig K v I"], assumption+, simp)
apply (frule Ig_nonzero[of v I],
frule val_nonzero_noninf[of v "Ig K v I"], assumption+,
simp add:val_noninf_n_val_noninf[of v "Ig K v I"],
frule val_poss_mem_Vr[of v "Pg K v"], assumption+,
subst n_value_idealTr[of v "na (n_val K v (Ig K v I))"],

apply (frule eq_val_eq_ideal[of v "Ig K v I"
"(Pg K v)^⇗(Vr K v) (na (n_val K v (Ig K v I)))⇖"], assumption+,
rule Ring.npClose, assumption+,
simp add:Vr_exp_f_exp[of v "Pg K v"],
subst val_exp_ring[THEN sym, of v "Pg K v"
"na (n_val K v (Ig K v I))"], assumption+)
apply (frule Lv_z[of v], erule exE, simp,
rotate_tac 6, drule sym, simp,
subst asprod_amult,
simp add:val_poss_n_val_poss[of v "Ig K v I"],
frule val_nonzero_noninf[of v "Ig K v I"], assumption+,
frule val_noninf_n_val_noninf[of v "Ig K v I"], assumption+, simp,
rule aposs_na_poss[of "n_val K v (Ig K v I)"], assumption+)
apply (fold an_def)
apply (subst an_na[THEN sym, of "n_val K v (Ig K v I)"],
frule val_nonzero_noninf[of v "Ig K v I"], assumption+,
frule val_noninf_n_val_noninf[of v "Ig K v I"], assumption+, simp,
apply simp
done

lemma (in Corps) ideal_apow_vp:"⟦valuation K v; ideal (Vr K v) I⟧ ⟹
I = (vp K v)⇗ (Vr K v) (n_val K v (Ig K v I))⇖"
apply (frule Vr_ring[of v])
apply (case_tac "v (Ig K v I) = ∞",
frule val_Ig[of v I], assumption,
frule val_inf_n_val_inf[of v "Ig K v I"],

apply (case_tac "v (Ig K v I) = 0",
frule val_0_n_val_0[of v "Ig K v I"],
frule val_Ig[of v I], assumption+, erule conjE,

frule val_Ig[of v I], assumption,
frule zero_val_gen_whole[of v "Ig K v I"],
frule Ring.ideal_cont_Rxa[of "Vr K v" "I" "Ig K v I"], assumption+)
apply (simp,
frule Ring.ideal_subset1[of "Vr K v" "I"], assumption+,
frule equalityI[of "I" "carrier (Vr K v)"], assumption+,
apply (frule val_noninf_n_val_noninf[of v "Ig K v I"],
frule val_Ig[of v I], assumption,
frule value_n0_n_val_n0[of v "Ig K v I"],
frule val_Ig[of v I], assumption,

rule ideal_pow_vp, assumption+,
frule elem_nonzeroval_gen_proper[of v "Ig K v I"],
frule val_Ig[of v I], assumption+, erule conjE,

apply (frule val_Ig[of v I], assumption+, erule conjE, simp,
done

(* A note to the above lemma (in Corps).
Let K be a field and v be a valuation. Let R be the valuaiton ring of v,
and let P be the maximal ideal of R. If I is an ideal of R such that I ≠ 0
and I ≠ R, then I = P^n. Here n = nat znt n_valuation K G a i v (I_gen
K v I)) which is nat of the integer part of the normal value of
(I_gen K v I).  Let b be a generator of I, then n = v (b) / v (p), where
p is a generator of P in R:
I = P ⇗♢R n⇖

Here
P = vp K v,
R = Vr K v,
b = Ig K v I,,
n = nat n_val K v (Ig K v I).
It is easy to see that n = v⇧* b. Here v⇧* is the normal valuation derived from
v. *)

lemma (in Corps) ideal_apow_n_val:"⟦valuation K v; x ∈ carrier (Vr K v)⟧ ⟹
(Vr K v) ♢⇩p x = (vp K v)⇗(Vr K v) (n_val K v x)⇖"
apply (frule Vr_ring[of v],
frule Ring.principal_ideal[of "Vr K v" "x"], assumption+,
frule ideal_apow_vp[of v "Vr K v ♢⇩p x"], assumption+)
apply (frule val_Ig[of v "Vr K v ♢⇩p x"], assumption+, erule conjE,
frule Ring.ideal_subset[of "Vr K v" "Vr K v ♢⇩p x"
"Ig K v (Vr K v ♢⇩p x)"], assumption+,
frule Ig_generate_I[of v "Vr K v ♢⇩p x"], assumption+)
apply (frule eq_ideal_eq_val[of v "Ig K v (Vr K v ♢⇩p x)" x],
assumption+,
thin_tac "Vr K v ♢⇩p Ig K v (Vr K v ♢⇩p x) = Vr K v ♢⇩p x",
thin_tac "v (Ig K v (Vr K v ♢⇩p x)) = LI K v (Vr K v ♢⇩p x)",
frule n_val[THEN sym, of v x],
thin_tac "v x = n_val K v x * Lv K v",
frule n_val[THEN sym, of v "Ig K v (Vr K v ♢⇩p x)"],
thin_tac "v (Ig K v (Vr K v ♢⇩p x)) = n_val K v x * Lv K v")
apply (frule Lv_pos[of v],
frule Lv_z[of v], erule exE, simp,
frule_tac s = z in zless_neq[THEN not_sym, of "0"],
frule_tac z = z in adiv_eq[of _ "n_val K v (Ig K v (Vr K v ♢⇩p x))"
"n_val K v x"], assumption+, simp)
done

lemma (in Corps) t_gen_vp:"⟦valuation K v; t ∈ carrier K; v t = 1⟧ ⟹
(Vr K v) ♢⇩p t = vp K v"
(*
apply (frule val_surj_n_val[of v], blast)
apply (frule ideal_apow_n_val[of v t])
apply (cut_tac a0_less_1)
apply (rule val_poss_mem_Vr[of v t], assumption+, simp)
apply (simp only:ant_1[THEN sym], simp only:ant_0[THEN sym])
apply (simp only:aeq_zeq, simp)
apply (cut_tac z_neq_inf[THEN not_sym, of "1"], simp)
apply (simp only:an_1[THEN sym]) apply (simp add:na_an)
apply (rule Ring.idealprod_whole_r[of "Vr K v" "vp K v"])
done *)

proof -
assume  a1:"valuation K v" and
a2:"t ∈ carrier K" and
a3:"v t = 1"
from a1 and a2 and a3 have h1:"t ∈ carrier (Vr K v)"
apply (cut_tac a0_less_1)
apply (rule val_poss_mem_Vr[of v t], assumption+, simp) done
from a1 and a2 and a3 have h2:"n_val K v = v"
apply (subst val_surj_n_val[of v]) apply assumption
apply blast  apply simp done
from a1 and h1 have h3:"Vr K v ♢⇩p t = vp K v⇗ (Vr K v) (n_val K v t)⇖"
apply (simp add:ideal_apow_n_val[of v t]) done
from a1 and a3 and h2 and h3 show ?thesis
apply (simp only:ant_1[THEN sym], simp only:ant_0[THEN sym])
apply (simp only:aeq_zeq, simp)
apply (cut_tac z_neq_inf[THEN not_sym, of "1"], simp)
apply (simp only:an_1[THEN sym]) apply (simp add:na_an)
apply (rule Ring.idealprod_whole_r[of "Vr K v" "vp K v"])
qed

lemma (in Corps) t_vp_apow:"⟦valuation K v; t ∈ carrier K; v t = 1⟧ ⟹
(Vr K v) ♢⇩p (t^⇗(Vr K v) n⇖) = (vp K v)⇗(Vr K v) (an n)⇖"
(*
apply (frule Vr_ring[of v],
subst Ring.principal_ideal_n_pow[THEN sym, of "Vr K v" t "vp K v" n],
assumption+)
apply (cut_tac a0_less_1, rule val_poss_mem_Vr[of v], assumption+)
apply (rule conjI, rule impI,
simp only:an_0[THEN sym], frule an_inj[of n 0], simp)
apply (rule impI)
apply (rule conjI, rule impI)
apply (rule impI, cut_tac an_nat_pos[of n], simp add:na_an)
done *)

proof -
assume  a1:"valuation K v" and
a2:"t ∈ carrier K" and
a3:"v t = 1"
from a1 have h1:"Ring (Vr K v)"  by (simp add:Vr_ring[of v])
from a1 and a2 and a3 have h2:"t ∈ carrier (Vr K v)"
apply (cut_tac a0_less_1)
apply (rule val_poss_mem_Vr) apply assumption+ apply simp done
from a1 and a2 and a3 and h1 and h2 show ?thesis
apply (subst Ring.principal_ideal_n_pow[THEN sym, of "Vr K v" t "vp K v" n])
apply assumption+
apply (rule conjI, rule impI,
simp only:an_0[THEN sym], frule an_inj[of n 0], simp)
apply (rule impI)
apply (rule conjI, rule impI)
apply (rule impI, cut_tac an_nat_pos[of n], simp add:na_an)
done
qed

lemma (in Corps) nonzeroelem_gen_nonzero:"⟦valuation K v; x ≠ 𝟬;
x ∈ carrier (Vr K v)⟧ ⟹  Vr K v ♢⇩p x ≠ {𝟬⇘Vr K v⇙}"
by (frule Vr_ring[of v],
frule_tac a = x in Ring.a_in_principal[of "Vr K v"], assumption+,

subsection "Amin lemma (in Corps)s "

lemma (in Corps)  Amin_le_addTr:"valuation K v ⟹
(∀j ≤ n. f j ∈ carrier K) ⟶ Amin n (v ∘ f) ≤ (v (nsum K f n))"
apply (induct_tac n)
apply (rule impI, simp)

apply (rule impI,
simp,
frule_tac x = "Σ⇩e K f n" and y = "f (Suc n)" in amin_le_plus[of v],
cut_tac field_is_ring, frule Ring.ring_is_ag[of "K"],
cut_tac n = n in aGroup.nsum_mem[of K _ f], assumption,
rule allI, simp add:funcset_mem, assumption, simp)
apply (frule_tac z = "Amin n (λu. v (f u))" and z' = "v (Σ⇩e K f n)" and
w = "v (f (Suc n))" in amin_aminTr,
rule_tac i = "amin (Amin n (λu. v (f u))) (v (f (Suc n)))" and
j = "amin (v (Σ⇩e K f n)) (v (f (Suc n)))" and
k = "v (Σ⇩e K f n ± (f (Suc n)))" in ale_trans, assumption+)
done

lemma (in Corps) Amin_le_add:"⟦valuation K v; ∀j ≤ n. f j ∈ carrier K⟧ ⟹
Amin n (v ∘ f) ≤ (v (nsum K f n))"
by (frule Amin_le_addTr[of v n f], simp)

lemma (in Corps) value_ge_add:"⟦valuation K v; ∀j ≤ n. f j ∈ carrier K;
∀j ≤ n. z ≤ ((v ∘ f) j)⟧  ⟹ z ≤ (v (Σ⇩e K f n))"
apply (frule Amin_le_add[of v n f], assumption+,
cut_tac Amin_ge[of n "v ∘ f" z],
rule ale_trans, assumption+)
apply (rule allI, rule impI,
rule value_in_aug_inf[of v], assumption+, simp+)
done

lemma (in Corps) Vr_ideal_powTr1:"⟦valuation K v; ideal (Vr K v) I;
I ≠ carrier (Vr K v); b ∈ I⟧  ⟹ b ∈ (vp K v)"
by (frule ideal_sub_vp[of v I], assumption+, simp add:subsetD)

section ‹pow of vp and ‹n_value› -- convergence --›

lemma (in Corps) n_value_x_1:"⟦valuation K v; 0 ≤ n;
x ∈ (vp K v) ⇗(Vr K v) n⇖⟧ ⟹  n ≤ (n_val K v x)"
(* 1. prove that x ∈ carrier (Vr K v) and that x ∈ carrier K *)
apply ((case_tac "n = ∞", simp add:r_apow_def,
frule Ring.ring_zero[of "K"], frule val_inf_n_val_inf[of v 𝟬],
(case_tac "n = 0", simp add:r_apow_def,
subst val_pos_n_val_pos[THEN sym, of v x], assumption+,
subst val_pos_mem_Vr[of v x], assumption+,
frule vp_pow_ideal[of v "na n"],
frule Ring.ideal_subset[of "Vr K v" "(vp K v) ⇗♢(Vr K v) (na n)⇖" x],
assumption+, frule Vr_mem_f_mem[of v x], assumption+))
(* 1. done *)

(** 2. Show that
v (I_gen K v (vpr K  v)^⇧Vr K v⇧ ⇧nat n) ≤ v x.  the key lemma (in Corps)  is
"val_Rxa_gt_a"                  **)

apply (case_tac "x = 𝟬⇘K⇙", simp,
frule value_of_zero[of v],

frule val_Pg[of v], erule conjE, simp, erule conjE,
frule Lv_pos[of v],
rotate_tac -4, frule sym, thin_tac "v (Pg K v) = Lv K v", simp,
frule val_poss_mem_Vr[of v "Pg K v"], assumption+,
frule val_Rxa_gt_a[of v "Pg K v^⇗(Vr K v) (na n)⇖" x],

frule Vr_integral[of v],
simp only:Vr_0_f_0[of v, THEN sym],
frule Idomain.idom_potent_nonzero[of "Vr K v" "Pg K v" "na n"],

apply (thin_tac "x ∈ Vr K v ♢⇩p (Pg K v^⇗(Vr K v) (na n)⇖)",
thin_tac "ideal (Vr K v) (Vr K v ♢⇩p (Pg K v^⇗(Vr K v) (na n)⇖))")

apply (simp add:Vr_exp_f_exp[of v "Pg K v"],
simp add:val_exp_ring[THEN sym, of v "Pg K v"],
simp add:n_val[THEN sym, of v x],
frule val_nonzero_z[of v "Pg K v"], assumption+,
erule exE, simp,
frule aposs_na_poss[of "n"], simp add: less_le,

frule_tac w = z in amult_pos_mono_r[of _ "ant (int (na n))"
"n_val K v x"], simp,
cut_tac an_na[of "n"], simp add:an_def, assumption+)
done

lemma (in Corps) n_value_x_1_nat:"⟦valuation K v; x ∈ (vp K v)⇗♢(Vr K v) n⇖ ⟧ ⟹
(an n) ≤ (n_val K v x)"
apply (cut_tac an_nat_pos[of "n"])
apply( frule n_value_x_1[of  "v" "an n" "x"], assumption+)
apply (case_tac "n = 0", simp, simp)
apply (cut_tac aless_nat_less[THEN sym, of "0" "n"])
apply simp
unfolding less_le
apply simp
apply (cut_tac an_neq_inf [of "n"])
apply simp
apply assumption
done

lemma (in Corps) n_value_x_2:"⟦valuation K v; x ∈ carrier (Vr K v);
n ≤ (n_val K v x);  0 ≤ n⟧ ⟹  x ∈ (vp K v) ⇗(Vr K v) n⇖"
apply (frule Vr_ring[of v],
frule val_Pg[of v], erule conjE,
simp, erule conjE, drule sym,
frule Lv_pos[of v], simp,
frule val_poss_mem_Vr[of v "Pg K v"], assumption+)

apply (case_tac "n = ∞",
simp add:r_apow_def, cut_tac inf_ge_any[of "n_val K v x"],
frule ale_antisym[of "n_val K v x" "∞"], assumption+,
frule val_inf_n_val_inf[THEN sym, of v "x"],
frule value_inf_zero[of v x],

apply (case_tac "n = 0",
subst n_value_idealTr[of v "na n"], assumption+,
apply (rule val_Rxa_gt_a_1[of v "Pg K v^⇗(Vr K v) (na n)⇖" x],
assumption+,
rule Ring.npClose, assumption+,
frule Vr_integral[of v],
frule val_poss_mem_Vr[of v "Pg K v"], assumption+,

rotate_tac -5, drule sym,
frule Lv_z[of v], erule exE, simp,
frule aposs_na_poss[of "n"], simp add: less_le,
simp add:asprod_amult, subst n_val[THEN sym, of v x],
assumption+,
subst amult_pos_mono_r[of _ "ant (int (na n))" "n_val K v x"],
assumption,
cut_tac an_na[of "n"], simp add:an_def, assumption+)
done

lemma (in Corps) n_value_x_2_nat:"⟦valuation K v; x ∈ carrier (Vr K v);
(an n) ≤ ((n_val K v) x)⟧ ⟹  x ∈ (vp K v)⇗♢(Vr K  v)  n⇖"
by (frule n_value_x_2[of v x "an n"], assumption+,
case_tac "an n = ∞", simp add:an_def, simp,
case_tac "n = 0", simp,
subgoal_tac "an n ≠ 0", simp, simp add:na_an,

lemma (in Corps) n_val_n_pow:"⟦valuation K v; x ∈ carrier (Vr K v); 0 ≤ n⟧ ⟹
(n ≤ (n_val K v x)) = (x ∈ (vp K v) ⇗(Vr K v)  n⇖)"

lemma (in Corps) eqval_in_vpr_apow:"⟦valuation K v; x ∈ carrier K; 0 ≤ n;
y ∈ carrier K; n_val K v x = n_val K v y; x ∈ (vp K v)⇗(Vr K v) n⇖⟧ ⟹
y ∈ (vp K v) ⇗(Vr K v) n⇖"
apply (frule n_value_x_1[of v n x], assumption+, simp,
rule n_value_x_2[of v y n], assumption+,
frule mem_vp_apow_mem_Vr[of v n x], assumption+)
apply (frule val_pos_mem_Vr[THEN sym, of v x], assumption+, simp,
simp add:val_pos_n_val_pos[THEN sym, of v y],
done

lemma (in Corps) convergenceTr:"⟦valuation K v; x ∈ carrier K; b ∈ carrier K;
b ∈ (vp K v)⇗(Vr K v) n⇖; (Abs (n_val K v x)) ≤ n⟧ ⟹
x ⋅⇩r b ∈ (vp K v)⇗(Vr K v) (n + (n_val K v x))⇖"
(** Valuation ring is a ring **)
apply (cut_tac Abs_pos[of "n_val K v x"],
frule ale_trans[of "0" "Abs (n_val K v x)" "n"], assumption+,
thin_tac "0 ≤ Abs (n_val K v x)")
apply (frule Vr_ring[of v],
frule_tac aadd_le_mono[of "Abs (n_val K v x)" "n" "n_val K v x"],
cut_tac Abs_x_plus_x_pos[of "n_val K v x"],
frule ale_trans[of "0" "Abs (n_val K v x) + n_val K v x"
"n + n_val K v x"], assumption+,
thin_tac "0 ≤ Abs (n_val K v x) + n_val K v x",
thin_tac "Abs (n_val K v x) + n_val K v x ≤ n + n_val K v x",
rule n_value_x_2[of v "x ⋅⇩r b" "n + n_val K v x"], assumption+)
apply (frule n_value_x_1[of v n b], assumption+)
apply (frule aadd_le_mono[of "n" "n_val K v b" "n_val K v x"],
frule ale_trans[of "0" "n + n_val K v x" "n_val K v b + n_val K v x"],
assumption)
apply (thin_tac "0 ≤ n + n_val K v x",
thin_tac "n ≤ n_val K v b",
thin_tac "n + n_val K v x ≤ n_val K v b + n_val K v x",
apply (frule n_val_valuation[of v],
simp add:val_t2p[THEN sym, of "n_val K v" x b],
cut_tac field_is_ring,
frule Ring.ring_tOp_closed[of "K" "x" "b"], assumption+,
simp add:val_pos_n_val_pos[THEN sym, of v "x ⋅⇩r b"],
frule n_val_valuation[of v],
subst val_t2p[of "n_val K v"], assumption+,
frule n_value_x_1[of v n b], assumption+,
rule aadd_le_mono[of n "n_val K v b" "n_val K v x"], assumption+)
done

lemma (in Corps) convergenceTr1:"⟦valuation K v; x ∈ carrier K;
b ∈ (vp K v)⇗(Vr K v) (n + Abs (n_val K v x))⇖; 0 ≤ n⟧ ⟹
x ⋅⇩r b ∈ (vp K v) ⇗(Vr K v) n⇖"
apply (cut_tac field_is_ring,
frule Vr_ring[of v],
frule vp_apow_ideal[of v "n + Abs (n_val K v x)"],
cut_tac Abs_pos[of "n_val K v x"],
rule aadd_two_pos[of "n" "Abs (n_val K v x)"], assumption+)

apply (frule Ring.ideal_subset[of "Vr K v" "vp K v⇗ (Vr K v) (n + Abs (n_val K v x))⇖"
"b"], assumption+,
frule Vr_mem_f_mem[of v b], assumption,
frule convergenceTr[of v x b "n +  Abs (n_val K v x)"], assumption+,
rule aadd_pos_le[of "n" "Abs (n_val K v x)"], assumption)

apply (frule  apos_in_aug_inf[of "n"],
cut_tac Abs_pos[of "n_val K v x"],
frule apos_in_aug_inf[of "Abs (n_val K v x)"],
frule n_value_in_aug_inf[of v x], assumption+,
frule aadd_assoc_i[of "n" "Abs (n_val K v x)" "n_val K v x"],
assumption+,
cut_tac Abs_x_plus_x_pos[of "n_val K v x"])

apply (frule_tac Ring.ring_tOp_closed[of K x b], assumption+,
rule n_value_x_2[of v "x ⋅⇩r b" n], assumption+)

apply (subst val_pos_mem_Vr[THEN sym, of v "x ⋅⇩r b"], assumption+,
subst val_pos_n_val_pos[of v "x ⋅⇩r b"], assumption+)

apply (frule n_value_x_1[of "v" "n + Abs(n_val K v x) + n_val K v x" "x ⋅⇩r b"],
rule ale_trans[of "0" "n + Abs (n_val K v x) + n_val K v x"
"n_val K v (x ⋅⇩r b)"],
frule n_value_x_1[of "v" "n + Abs (n_val K v x)" " b"],
cut_tac Abs_pos[of "n_val K v x"],
rule aadd_two_pos[of "n" "Abs (n_val K v x)"], assumption+)

apply (frule n_val_valuation[of v],
subst val_t2p[of  "n_val K v"], assumption+)
apply (frule aadd_le_mono[of "n + Abs (n_val K v x)" "n_val K v b"
"n_val K v x"],
rule ale_trans[of "n" "n + (Abs (n_val K v x) + n_val K v x)"
"n_val K v x + n_val K v b"],
frule aadd_pos_le[of "Abs (n_val K v x) + n_val K v x" "n"],
done

lemma (in Corps) vp_potent_zero:"⟦valuation K v; 0 ≤ n⟧ ⟹
(n = ∞) = (vp K v ⇗(Vr K v) n⇖ = {𝟬⇘Vr K v⇙})"
apply (rule iffI)
apply (simp add:r_apow_def, rule contrapos_pp, simp+,
frule apos_neq_minf[of "n"],
cut_tac mem_ant[of "n"], simp, erule exE, simp,
simp add:ant_0[THEN sym], thin_tac "n = ant z")

frule Vr_ring[of v],
frule Ring.ring_one[of "Vr K v"], simp,
frule value_of_one[of v], simp, simp add:value_of_zero,
cut_tac n = z in zneq_aneq[of _ "0"], simp only:ant_0)
frule_tac n = "na (ant z)" in n_value_idealTr[of v],
simp, thin_tac "vp K v ⇗♢(Vr K v) (na (ant z))⇖ = {𝟬⇘Vr K v⇙}",
frule Vr_ring[of v],
frule  Pg_in_Vr[of v],
frule_tac n = "na (ant z)" in Ring.npClose[of "Vr K v" "Pg K v"],
assumption)
apply (frule_tac a = "(Pg K v)^⇗(Vr K v) (na (ant z))⇖" in
Ring.a_in_principal[of "Vr K v"], assumption,
simp, frule Vr_integral[of "v"],
frule val_Pg[of v], simp, (erule conjE)+,
frule_tac n = "na (ant z)" in Idomain.idom_potent_nonzero[of "Vr K v"
"Pg K v"], assumption+,
done

lemma (in Corps) Vr_potent_eqTr1:"⟦valuation K v; 0 ≤ n; 0 ≤ m;
(vp K v) ⇗(Vr K v) n⇖ = (vp K v) ⇗(Vr K v) m⇖; m = 0⟧  ⟹  n = m"
(*** compare the value of the generator of each ideal ***)
(** express each ideal as a principal ideal **)
apply (frule Vr_ring[of v],
case_tac "n = 0", simp,
case_tac "n = ∞", simp,
frule val_Pg[of v], erule conjE, simp,
erule conjE,
rotate_tac -3, drule sym,
frule Lv_pos[of v], simp,
frule val_poss_mem_Vr[of v "Pg K v"], assumption+,

apply (simp,
drule sym,
frule Ring.ring_one[of "Vr K v"], simp,

frule n_value_x_1_nat[of v "1⇩r⇘(Vr K v)⇙" "na n"], assumption,
frule n_val_valuation[of v],
done

lemma (in Corps) Vr_potent_eqTr2:"⟦valuation K v;
(vp K v) ⇗♢(Vr K v) n⇖ = (vp K v) ⇗♢(Vr K v) m⇖⟧  ⟹   n = m"

(** 1. express each ideal as a principal ideal **)
apply (frule Vr_ring[of v],
frule val_Pg[of v], simp, (erule conjE)+,
rotate_tac -1, frule sym, thin_tac "v (Pg K v) = Lv K v",
frule Lv_pos[of v], simp)

apply (subgoal_tac "0 ≤ int n", subgoal_tac "0 ≤ int m",
frule n_value_idealTr[of "v" "m"]) apply simp apply simp
apply(
thin_tac "vp K v ⇗♢(Vr K v) m⇖ = Vr K v ♢⇩p (Pg K v^⇗(Vr K v) m⇖)",
frule n_value_idealTr[of "v" "n"], simp, simp,
thin_tac "vp K v ⇗♢(Vr K v) n⇖ = Vr K v ♢⇩p (Pg K v^⇗(Vr K v) m⇖)",
frule val_poss_mem_Vr[of  "v" "Pg K v"], assumption+)

(** 2. the value of generators should coincide **)
apply (frule Lv_z[of v], erule exE,
rotate_tac -4, drule sym, simp,
frule eq_ideal_eq_val[of "v" "Pg K v^⇗(Vr K v) n⇖" "Pg K v^⇗(Vr K v) m⇖"])
apply (rule Ring.npClose, assumption+, rule Ring.npClose, assumption+)
apply (simp only:Vr_exp_f_exp,
simp add:val_exp_ring[THEN sym, of v "Pg K v"],
thin_tac "Vr K v ♢⇩p (Pg K v^⇗K n⇖) = Vr K v ♢⇩p (Pg K v^⇗K m⇖)")

apply (case_tac "n = 0", simp, case_tac "m = 0", simp,
simp only:of_nat_0_less_iff[THEN sym, of "m"],
simp only:asprod_amult a_z_z,
simp only:ant_0[THEN sym], simp only:aeq_zeq, simp)
done

lemma (in Corps) Vr_potent_eq:"⟦valuation K v; 0 ≤ n; 0 ≤ m;
(vp K v) ⇗(Vr K v) n⇖ = (vp K v) ⇗(Vr K v) m⇖⟧ ⟹  n = m"
apply (frule n_val_valuation[of v],
case_tac "m = 0",
apply (case_tac "n = 0",
frule sym, thin_tac "vp K v⇗ (Vr K v) n⇖ = vp K v⇗ (Vr K v) m⇖",
frule Vr_potent_eqTr1[of v m n], assumption+,
rule sym, assumption,
frule vp_potent_zero[of  "v" "n"], assumption+)
apply (case_tac "n = ∞", simp,
thin_tac "vp K v⇗ (Vr K v) ∞⇖ = {𝟬⇘Vr K v⇙}",
frule vp_potent_zero[THEN sym, of v m], assumption+, simp,
simp,
frule vp_potent_zero[THEN sym, of v "m"], assumption+, simp,
thin_tac "vp K v⇗ (Vr K v) m⇖ ≠ {𝟬⇘Vr K v⇙}")

apply (frule aposs_na_poss[of "n"], subst less_le, simp,
frule aposs_na_poss[of "m"], subst less_le, simp,
frule Vr_potent_eqTr2[of  "v" "na n" "na m"], assumption+,
thin_tac "vp K v ⇗♢(Vr K v) (na n)⇖ = vp K v ⇗♢(Vr K v) (na m)⇖",
done

text‹the following two lemma (in Corps) s are used in completion of K›

lemma (in Corps) Vr_prime_maximalTr1:"⟦valuation K v; x ∈ carrier (Vr K v);
Suc 0 < n⟧  ⟹ x ⋅⇩r⇘(Vr K v)⇙ (x^⇗K (n - Suc 0)⇖) ∈ (Vr K v) ♢⇩p (x^⇗K n⇖)"
apply (frule Vr_ring[of v],
subgoal_tac "x^⇗K n⇖ = x^⇗K (Suc (n - Suc 0))⇖",
simp del:Suc_pred,
rotate_tac -1, drule sym)
apply (subst Vr_tOp_f_tOp, assumption+,
subst Vr_exp_f_exp[of v, THEN sym], assumption+,
simp only:Ring.npClose, simp del:Suc_pred)
apply (cut_tac field_is_ring,
frule Ring.npClose[of K x "n - Suc 0"],
frule Vr_mem_f_mem[of v x], assumption+,
frule Vr_mem_f_mem[of v x], assumption+)
apply (simp add:Ring.ring_tOp_commute[of K x "x^⇗K (n - Suc 0)⇖"])
apply (rule Ring.a_in_principal, assumption)
apply (frule Ring.npClose[of "Vr K v" x n], assumption,
apply (simp only:Suc_pred)
done

lemma (in Corps) Vr_prime_maximalTr2:"⟦ valuation K v; x ∈ vp K v; x ≠ 𝟬;
Suc 0 < n⟧ ⟹ x ∉ Vr K v ♢⇩p (x^⇗K n⇖) ∧ x^⇗K (n - Suc 0)⇖ ∉ (Vr K v) ♢⇩p (x^⇗K n⇖)"
apply (frule Vr_ring[of v])
apply (frule vp_mem_Vr_mem[of v x], assumption,
frule Ring.npClose[of "Vr K v" x n],
simp only:Vr_exp_f_exp)
apply (cut_tac field_is_ring,
cut_tac field_is_idom,
frule Vr_mem_f_mem[of v x], assumption+,
frule Idomain.idom_potent_nonzero[of K x n], assumption+)
apply (rule conjI)
apply (rule contrapos_pp, simp+)
apply (frule val_Rxa_gt_a[of v "x^⇗K n⇖" x],
apply (simp add:val_exp_ring[THEN sym, of v x n])
apply (frule val_nonzero_z[of v x], assumption+, erule exE,
apply (rule contrapos_pp, simp+)
apply (frule val_Rxa_gt_a[of v "x^⇗K n⇖" "x^⇗K (n - Suc 0)⇖"])
apply (simp, frule Ring.npClose[of "Vr K v" "x" "n - Suc 0"], assumption+)
apply (frule Ring.npClose[of "Vr K v" "x" "n - Suc 0"], assumption+,
apply (simp add:val_exp_ring[THEN sym, of v x])
apply (frule val_nonzero_z[of  "v" "x"], assumption+, erule exE,
done

lemma (in Corps) Vring_prime_maximal:"⟦valuation K v; prime_ideal (Vr K v) I;
I ≠ {𝟬⇘Vr K v⇙}⟧ ⟹ maximal_ideal (Vr K v) I"
apply (frule Vr_ring[of v],
frule Ring.prime_ideal_proper[of "Vr K v" "I"], assumption+,
frule Ring.prime_ideal_ideal[of "Vr K v" "I"], assumption+,
frule ideal_pow_vp[of v I],
frule n_value_idealTr[of "v" "na (n_val K v (Ig K v I))"],
simp, simp, assumption+)

apply (case_tac "na (n_val K v (Ig K v I)) = 0",
simp, frule Ring.Rxa_one[of "Vr K v"], simp,
frule Suc_leI[of "0" "na (n_val K v (Ig K v I))"],
thin_tac "0 < na (n_val K v (Ig K v I))")
apply (case_tac "na (n_val K v (Ig K v I)) = Suc 0", simp,
frule Pg_in_Vr[of v])
apply (frule vp_maximal[of v],
frule Ring.maximal_ideal_ideal[of "Vr K v" "vp K v"], assumption+,
subst Ring.idealprod_whole_r[of "Vr K v" "vp K v"], assumption+)

apply (rotate_tac -1, drule not_sym,
frule le_neq_implies_less[of "Suc 0" "na (n_val K v (Ig K v I))"],
assumption+,
thin_tac "Suc 0 ≤ na (n_val K v (Ig K v I))",
thin_tac "Suc 0 ≠ na (n_val K v (Ig K v I))",
thin_tac "Vr K v ♢⇩p 1⇩r⇘Vr K v⇙ = carrier (Vr K v)")
apply (frule val_Pg[of v], simp, (erule conjE)+,
frule Lv_pos[of v], rotate_tac -2, drule sym)
apply (frule val_poss_mem_Vr[of "v" "Pg K v"],
frule vp_mem_val_poss[THEN sym, of "v" "Pg K v"], assumption+, simp)

apply (frule Vr_prime_maximalTr2[of v "Pg K v"
"na (n_val K v (Ig K v I))"],
simp add:vp_mem_val_poss[of v "Pg K v"], assumption+, erule conjE)
apply (frule Ring.npMulDistr[of "Vr K v" "Pg K v" "na 1" "na (n_val K v (Ig K v I)) - Suc 0"], assumption+, simp add:na_1)

apply (rotate_tac 8, drule sym)
apply (frule Ring.a_in_principal[of "Vr K v"
"Pg K v^⇗(Vr K v) (na (n_val K v (Ig K v I)))⇖"], simp add:Ring.npClose)

apply (simp add:Ring.ring_l_one[of "Vr K v"])
apply (frule n_value_idealTr[THEN sym,
of v "na (n_val K v (Ig K v I))"], simp)
apply (rotate_tac 6, drule sym, simp)
apply (thin_tac "I ≠ carrier (Vr K v)",
thin_tac "I = vp K v ⇗♢(Vr K v) (na (n_val K v (Ig K v I)))⇖",
thin_tac "v (Pg K v) = Lv K v",
thin_tac "(Vr K v) ♢⇩p ((Pg K v) ⋅⇩r⇘(Vr K v)⇙
((Pg K v)^⇗K (na ((n_val K v) (Ig K v I)) - (Suc 0))⇖)) =
I",
thin_tac "Pg K v ∈ carrier K",
thin_tac "Pg K v ≠ 𝟬",
thin_tac "Pg K v^⇗K (na ((n_val K v) (Ig K v I)))⇖ =
Pg K v ⋅⇩r⇘Vr K v⇙ Pg K v^⇗K ((na ((n_val K v) (Ig K v I))) - Suc 0)⇖")

drule_tac x = "Pg K v" in bspec, assumption,
drule_tac x = "Pg K v^⇗K (na (n_val K v (Ig K v I)) - Suc 0)⇖ " in bspec)
apply (simp add:Vr_exp_f_exp[THEN sym, of v])
apply (rule Ring.npClose[of "Vr K v" "Pg K v"], assumption+)
apply simp
done

text‹From the above lemma (in Corps) , we see that a valuation ring is of dimension one.›

lemma (in Corps) field_frac1:"⟦1⇩r ≠ 𝟬; x ∈ carrier K⟧ ⟹ x = x ⋅⇩r ((1⇩r)⇗‐K⇖)"
cut_tac field_is_ring,

lemma (in Corps) field_frac2:"⟦x ∈ carrier K; x ≠ 𝟬⟧ ⟹ x = (1⇩r) ⋅⇩r ((x⇗‐K⇖)⇗‐K⇖)"

lemma (in Corps) val_nonpos_inv_pos:"⟦valuation K v; x ∈ carrier K;
¬ 0 ≤ (v x)⟧  ⟹ 0 < (v (x⇗‐K⇖))"
by (case_tac "x = 𝟬⇘K⇙", simp add:value_of_zero,
frule Vr_ring[of v],
frule value_of_inv[THEN sym, of v x], assumption+,
frule aless_minus[of "v x" "0"], simp)

lemma (in Corps) frac_Vr_is_K:"⟦valuation K v; x ∈ carrier K⟧ ⟹
∃s∈carrier (Vr K v). ∃t∈carrier (Vr K v) - {𝟬}. x = s ⋅⇩r (t⇗‐K⇖)"
apply (frule Vr_ring[of v],
frule has_val_one_neq_zero[of v])
apply (case_tac "x = 𝟬⇘K⇙",
frule Ring.ring_one[of "Vr K v"],
frule field_frac1[of x],
simp only:Vr_1_f_1, frule Ring.ring_zero[of "Vr K v"],
apply (case_tac "0 ≤ (v x)",
frule val_pos_mem_Vr[THEN sym, of v x], assumption+, simp,
frule field_frac1[of x], assumption+,
frule has_val_one_neq_zero[of v],
frule Ring.ring_one[of "Vr K v"], simp only:Vr_1_f_1, blast)
apply (frule val_nonpos_inv_pos[of v x], assumption+,
cut_tac invf_inv[of x], erule conjE,
frule val_poss_mem_Vr[of v "x⇗‐K⇖"], assumption+)
apply (frule Ring.ring_one[of "Vr K v"], simp only:Vr_1_f_1,
frule field_frac2[of x], assumption+)
apply (cut_tac invf_closed1[of x], blast, simp+)
done

lemma (in Corps) valuations_eqTr1:"⟦valuation K v; valuation K v';
Vr K v = Vr K v'; ∀x∈carrier (Vr K v). v x = v' x⟧ ⟹ v = v'"
apply (rule funcset_eq [of _  "carrier K"],
rule ballI,
frule_tac x = x in frac_Vr_is_K[of v], assumption+,
(erule bexE)+, simp, erule conjE)
apply (frule_tac x = t in Vr_mem_f_mem[of v'], assumption,
cut_tac x = t in invf_closed1, simp, simp, erule conjE)
apply (frule_tac x = s in Vr_mem_f_mem[of "v'"], assumption+,
done

lemma (in Corps) ridmap_rhom:"⟦ valuation K v; valuation K v';
carrier (Vr K v) ⊆ carrier (Vr K v')⟧ ⟹
ridmap (Vr K v) ∈ rHom (Vr K v) (Vr K v')"
apply (frule Vr_ring[of "v"], frule Vr_ring[of "v'"],
subst rHom_def, simp, rule conjI)
(rule ballI)+,
frule Ring.ring_is_ag[of "Vr K v"], simp add:aGroup.ag_pOp_closed,
apply (rule conjI, (rule ballI)+, simp add:ridmap_def,
frule Ring.ring_one[of "Vr K v"], frule Ring.ring_one[of "Vr K v'"],
done

lemma (in Corps) contract_ideal:"⟦valuation K v; valuation K v';
carrier (Vr K v) ⊆ carrier (Vr K v')⟧ ⟹
ideal (Vr K v) (carrier (Vr K v) ∩ vp K v')"
apply (frule_tac ridmap_rhom[of "v" "v'"], assumption+,
frule Vr_ring[of "v"], frule Vr_ring[of "v'"])
apply (cut_tac TwoRings.i_contract_ideal[of "Vr K v" "Vr K v'"
"ridmap (Vr K v)" "vp K v'"],
subgoal_tac "(i_contract (ridmap (Vr K v)) (Vr K v) (Vr K v')
(vp K v')) = (carrier (Vr K v) ∩ vp K v')")
apply simp
apply(thin_tac "ideal (Vr K v) (i_contract (ridmap (Vr K v))
(Vr K v) (Vr K v') (vp K v'))",
done

lemma (in Corps) contract_prime:"⟦valuation K v; valuation K v';
carrier (Vr K v) ⊆ carrier (Vr K v')⟧  ⟹
prime_ideal (Vr K v) (carrier (Vr K v) ∩ vp K v')"
apply (frule_tac ridmap_rhom[of "v" "v'"], assumption+,
frule Vr_ring[of "v"],
frule Vr_ring[of "v'"],
cut_tac TwoRings.i_contract_prime[of "Vr K v" "Vr K v'" "ridmap (Vr K v)"
"vp K v'"])
apply (subgoal_tac "(i_contract (ridmap (Vr K v)) (Vr K v) (Vr K v')
(vp K v')) = (carrier (Vr K v) ∩ vp K v')",
simp,
thin_tac "prime_ideal (Vr K v) (i_contract
(ridmap (Vr K v))  (Vr K  v) (Vr K v') (vp K v'))",
done

(* ∀x∈carrier K. 0 ≤ (v x) ⟶ 0 ≤ (v' x) *)
lemma (in Corps) valuation_equivTr:"⟦valuation K v; valuation K v';
x ∈ carrier K;  0 < (v' x); carrier (Vr K v) ⊆ carrier (Vr K v')⟧
⟹ 0 ≤ (v x)"
apply (rule contrapos_pp, simp+,
frule val_nonpos_inv_pos[of "v" "x"], assumption+,
case_tac "x = 𝟬⇘K⇙", simp add:value_of_zero[of "v"]) apply (
cut_tac invf_closed1[of  "x"], simp, erule conjE,
frule aless_imp_le[of "0" "v (x⇗‐K⇖)"])
frule subsetD[of "carrier (Vr K v)" "carrier (Vr K v')" "x⇗‐K⇖"],
assumption+,
frule val_pos_mem_Vr[THEN sym, of "v'" "x⇗‐K⇖"], assumption+)
apply (simp, simp add:value_of_inv[of "v'" "x"],
cut_tac ale_minus[of "0" "- v' x"], thin_tac "0 ≤ - v' x",
simp only:a_minus_minus,
cut_tac aneg_less[THEN sym, of "v' x" "- 0"], simp,
assumption, simp)
done

lemma (in Corps) contract_maximal:"⟦valuation K v; valuation K v';
carrier (Vr K v) ⊆ carrier (Vr K v')⟧ ⟹
maximal_ideal (Vr K v) (carrier (Vr K v) ∩ vp K v')"
apply (frule Vr_ring[of "v"],
frule Vr_ring[of "v'"],
rule Vring_prime_maximal, assumption+,
apply (frule vp_nonzero[of  "v'"],
frule vp_ideal[of  "v'"],
frule Ring.ideal_zero[of "Vr K v'" "vp K v'"], assumption+,
frule sets_not_eq[of "vp K v'" "{𝟬⇘(Vr K v')⇙}"],
simp add: singleton_sub[of "𝟬⇘(Vr K v')⇙" "carrier (Vr K v')"],

apply (case_tac "a ∈ carrier (Vr K v)", blast,
frule_tac x = a in vp_mem_Vr_mem[of "v'"], assumption+,
frule_tac x = a in Vr_mem_f_mem[of  "v'"], assumption+,
subgoal_tac "a ∈ carrier (Vr K v)", blast,
frule_tac x1 = a in val_pos_mem_Vr[THEN sym, of "v"], assumption+,
simp, frule val_nonpos_inv_pos[of  "v"], assumption+)

apply (frule_tac y = "v (a⇗‐K⇖)" in aless_imp_le[of "0"],
cut_tac x = a in invf_closed1, simp,
frule_tac x = "a⇗‐K⇖" in val_poss_mem_Vr[of v], simp, assumption+)
apply (frule_tac c = "a⇗‐K⇖" in subsetD[of "carrier (Vr K v)"
"carrier (Vr K v')"], assumption+) apply (
frule_tac x = "a⇗‐K⇖" in val_pos_mem_Vr[of "v'"],
simp, simp only:value_of_inv[of "v'"], simp,
apply (frule_tac y = "- v' a" in ale_minus[of "0"], simp add:a_minus_minus,
frule_tac x = a in vp_mem_val_poss[of "v'"], assumption+,
simp)
done

section "Equivalent valuations"

definition
v_equiv :: "[_ , 'r ⇒ ant, 'r ⇒ ant] ⇒ bool" where
"v_equiv K v1 v2 ⟷ n_val K v1 = n_val K v2"

lemma (in Corps) valuation_equivTr1:"⟦valuation K v; valuation K v';
∀x∈carrier K. 0 ≤ (v x) ⟶ 0 ≤ (v' x)⟧ ⟹
carrier (Vr K v) ⊆ carrier (Vr K v')"
apply (frule Vr_ring[of  "v"],
frule Vr_ring[of  "v'"])
apply (rule subsetI,
case_tac "x = 𝟬⇘K⇙", simp, simp add:Vr_def Sr_def,
frule_tac x1 = x in val_pos_mem_Vr[THEN sym, of "v"],
frule_tac x = x in Vr_mem_f_mem[of "v"],
simp, frule_tac x = x in Vr_mem_f_mem[of "v"], assumption+)
apply (drule_tac x = x in bspec, simp add:Vr_mem_f_mem)
apply simp
apply (subst val_pos_mem_Vr[THEN sym, of v'], assumption+,
done

lemma (in Corps) valuation_equivTr2:"⟦valuation K v; valuation K v';
carrier (Vr K v) ⊆ carrier (Vr K v'); vp K v = carrier (Vr K v) ∩ vp K v'⟧
⟹  carrier (Vr K v') ⊆ carrier (Vr K v)"
apply (frule Vr_ring[of "v"], frule Vr_ring[of "v'"])
apply (rule subsetI)
apply (case_tac "x = 𝟬⇘(Vr K v')⇙", simp,
subst Vr_0_f_0[of "v'"], assumption+,
subst Vr_0_f_0[of "v", THEN sym], assumption,
apply (rule contrapos_pp, simp+)
apply (frule_tac x = x in Vr_mem_f_mem[of "v'"], assumption+)
apply (simp add:val_pos_mem_Vr[THEN sym, of "v"])
apply (cut_tac y = "v x" in aneg_le[of "0"], simp)
apply (frule_tac x = "v x" in aless_minus[of _ "0"], simp,
thin_tac "v x < 0", thin_tac "¬ 0 ≤ v x")
apply (simp add:value_of_inv[THEN sym, of "v"])
apply (cut_tac x = x in invf_closed1, simp, simp, erule conjE)
apply (frule_tac x1 = "x⇗‐K⇖" in vp_mem_val_poss[THEN sym, of "v"],
assumption, simp, erule conjE)
apply (frule vp_ideal [of "v'"])
apply (frule_tac x = "x⇗‐K⇖" and r = x in Ring.ideal_ring_multiple[of "Vr K v'"
"vp K v'"], assumption+)
apply (frule_tac x = "x⇗‐K⇖" in vp_mem_Vr_mem[of "v'"], assumption+)
apply (frule_tac x = x and y = "x⇗‐K⇖" in Ring.ring_tOp_commute[of "Vr K v'"],
assumption+, simp,
thin_tac "x ⋅⇩r⇘Vr K v'⇙ x⇗‐ K⇖ = x⇗‐ K⇖ ⋅⇩r⇘Vr K v'⇙ x")
apply (cut_tac x = x in  linvf, simp, simp)
apply (cut_tac field_is_ring, frule Ring.ring_one[of "K"])
apply (frule ideal_inc_elem0val_whole[of "v'" "1⇩r" "vp K v'"],
apply (frule vp_not_whole[of "v'"], simp)
done

lemma (in Corps) eq_carr_eq_Vring:" ⟦valuation K v; valuation K v';
carrier (Vr K v) = carrier (Vr K v')⟧ ⟹ Vr K v = Vr K v'"
done

lemma (in Corps) valuations_equiv:"⟦valuation K v; valuation K v';
∀x∈carrier K. 0 ≤ (v x) ⟶ 0 ≤ (v' x)⟧  ⟹ v_equiv K v v'"
(** step0. preliminaries. **)
apply (frule Vr_ring[of "v"], frule Vr_ring[of "v'"])

(** step1.  show carrier (Vr K v) ⊆ carrier (Vr K v') **)
apply (frule valuation_equivTr1[of "v" "v'"], assumption+)

(** step2.  maximal_ideal (Vr K v) (carrier (Vr K v) ∩ (vp K v')).
contract of the maximal ideal is prime, and a prime is maximal **)
apply (frule contract_maximal [of "v" "v'"], assumption+)

(** step3. Vring is a local ring, we have (vp K v) =
(carrier (Vr K v) ∩ (vp  K v')) **)
apply (frule Vr_local[of "v" "(carrier (Vr K v) ∩ vp K v')"],
assumption+)

(** step4. show  carrier (Vr K v') ⊆ carrier (Vr K v) **)
apply (frule valuation_equivTr2[of "v" "v'"], assumption+,
frule equalityI[of "carrier (Vr K v)" "carrier (Vr K v')"],
assumption+,
thin_tac "carrier (Vr K v) ⊆ carrier (Vr K v')",
thin_tac "carrier (Vr K v') ⊆ carrier (Vr K v)")
(** step5. vp K v' = vp K v **)
apply (frule vp_ideal[of "v'"],
frule Ring.ideal_subset1[of "Vr K v'" "vp K v'"], assumption,
thin_tac "∀x∈carrier K. 0 ≤ v x ⟶ 0 ≤ v' x",
thin_tac "vp K v' ⊆ carrier (Vr K v')",
thin_tac "ideal (Vr K v') (vp K v')",
thin_tac "maximal_ideal (Vr K v) (vp K v')")
(** step6. to show v_equiv K v v', we check whether the normal valuations
derived from the valuations have the same value or not. if (Vr K
(n_valuation K v)) = (Vr K (n_valuation K v')), then we have only to
check the values of the elements in this valuation ring.
We see (Vr K v) = (Vr K  (n_valuation K G a i v)). **)
rule valuations_eqTr1[of  "n_val K v" "n_val K v'"],
rule eq_carr_eq_Vring[of  "n_val K v" "n_val K v'"],
subst Vr_n_val_Vr[THEN sym, of "v"], assumption+,
subst Vr_n_val_Vr[THEN sym, of "v'"], assumption+)
apply (rule ballI,
frule n_val_valuation[of "v"],
frule n_val_valuation[of "v'"],
frule_tac x1 = x in val_pos_mem_Vr[THEN sym, of "n_val K v"],
frule Vr_n_val_Vr[THEN sym, of "v"], simp,
thin_tac "carrier (Vr K (n_val K v)) = carrier (Vr K v')",
frule_tac x1 = x in val_pos_mem_Vr[THEN sym, of "v'"],
simp,
frule_tac x = x in val_pos_n_val_pos[of "v'"],
frule_tac x = x in ideal_apow_n_val[of "v"],
simp add:Vr_n_val_Vr[THEN sym, of "v"], simp)
apply (frule eq_carr_eq_Vring[of "v" "v'"], assumption+,
frule_tac x = x in ideal_apow_n_val[of "v'"], assumption,
thin_tac "Vr K v' ♢⇩p x = vp K v'⇗ (Vr K v') (n_val K v x)⇖",
frule_tac n = "n_val K v' x" and m = "n_val K v x" in
Vr_potent_eq[of  "v'"], assumption+,
frule sym, assumption+)
done

lemma (in Corps) val_equiv_axiom1:"valuation K v ⟹ v_equiv K v v"
done

lemma (in Corps) val_equiv_axiom2:"⟦ valuation K v; valuation K v';
v_equiv K v v'⟧ ⟹ v_equiv K v' v"
done

lemma (in Corps) val_equiv_axiom3:"⟦ valuation K v; valuation K v';
valuation K v'; v_equiv K v v'; v_equiv K v' v''⟧ ⟹  v_equiv K v v''"
done

lemma (in Corps) n_val_equiv_val:"⟦ valuation K v⟧ ⟹
v_equiv K v (n_val K v)"
apply (frule valuations_equiv[of "v" "n_val K v"], simp add:n_val_valuation)
apply (rule ballI, rule impI, simp add:val_pos_n_val_pos,
assumption)
done

section "Prime divisors"

definition
prime_divisor :: "[_, 'b ⇒ ant] ⇒
('b ⇒ ant) set"  ("(2P⇘ _ _⇙)" [96,97]96) where
"P⇘K v⇙ = {v'. valuation K v' ∧ v_equiv K v v'}"

definition
prime_divisors :: "_ ⇒ ('b ⇒ ant) set set" ("Pdsı" 96) where
"Pds⇘K⇙ = {P. ∃v. valuation K v ∧ P = P⇘ K v⇙ }"

definition
normal_valuation_belonging_to_prime_divisor ::
"[_ ,  ('b ⇒ ant) set] ⇒ ('b ⇒ ant)"  ("(ν⇘_ _⇙)" [96,97]96) where
"ν⇘K P⇙ = n_val K (SOME v. v ∈ P)"

lemma (in Corps) val_in_P_valuation:"⟦valuation K v; v' ∈ P⇘K v⇙⟧ ⟹
valuation K v'"
done

lemma (in Corps) vals_in_P_equiv:"⟦ valuation K v; v' ∈ P⇘K v⇙⟧ ⟹
v_equiv K v v'"
done

lemma (in Corps) v_in_prime_v:"valuation K v ⟹ v ∈ P⇘K v⇙"
frule val_equiv_axiom1[of "v"], assumption+)
done

lemma (in Corps) some_in_prime_divisor:"valuation K v ⟹
(SOME w. w ∈ P⇘K v⇙) ∈  P⇘K v⇙"
apply (subgoal_tac "P⇘ K v⇙ ≠ {}",
rule nonempty_some[of "P⇘ K v⇙"], assumption+,
frule v_in_prime_v[of "v"])
apply blast
done

lemma (in Corps) valuation_some_in_prime_divisor:"valuation K v
⟹  valuation K (SOME w. w ∈ P⇘K v⇙)"
apply (frule some_in_prime_divisor[of "v"],
done

lemma (in Corps) valuation_some_in_prime_divisor1:"P ∈ Pds  ⟹
valuation K (SOME w. w ∈ P)"
done

lemma (in Corps) representative_of_pd_valuation:
"P ∈ Pds ⟹ valuation K (ν⇘K P⇙)"
erule exE, erule conjE,
frule_tac v = v in valuation_some_in_prime_divisor)

apply (rule n_val_valuation, assumption+)
done

lemma (in Corps) some_in_P_equiv:"valuation K v ⟹
v_equiv K v (SOME w. w ∈ P⇘K v⇙)"
apply (frule some_in_prime_divisor[of v])
apply (rule vals_in_P_equiv, assumption+)
done

lemma (in Corps) n_val_n_val1:"P ∈ Pds  ⟹ n_val K (ν⇘K P⇙) = (ν⇘K P⇙)"
frule valuation_some_in_prime_divisor1[of P])
apply (rule n_val_n_val[of "SOME v. v ∈ P"], assumption+)
done

lemma (in Corps) P_eq_val_equiv:"⟦valuation K v; valuation K v'⟧ ⟹
(v_equiv K v v') = (P⇘K v⇙ =  P⇘K v'⇙)"
apply (rule iffI,
rule equalityI,
rule subsetI, simp add:prime_divisor_def, erule conjE,
frule val_equiv_axiom2[of "v" "v'"], assumption+,
rule val_equiv_axiom3[of "v'" "v"], assumption+,
rule subsetI, simp add:prime_divisor_def, erule conjE)
apply (rule val_equiv_axiom3[of "v" "v'"], assumption+,
frule v_in_prime_v[of  "v"], simp,
thin_tac "P⇘K v⇙ = P⇘K v'⇙",