(* Title: Psi-calculi Author/Maintainer: Jesper Bengtson (jebe@itu.dk), 2012 *) theory Frame imports Agent begin lemma permLength[simp]: fixes p :: "name prm" and xvec :: "'a::pt_name list" shows "length(p ∙ xvec) = length xvec" by(induct xvec) auto