Graph Lemma

Štěpán Holub 🌐 and Štěpán Starosta 🌐

May 24, 2021

This is a development version of this entry. It might change over time and is not stable. Please refer to release versions for citations.


Graph lemma quantifies the defect effect of a system of word equations. That is, it provides an upper bound on the rank of the system. We formalize the proof based on the decomposition of a solution into its free basis. A direct application is an alternative proof of the fact that two noncommuting words form a code.


BSD License


August 24, 2022
Reworked version. Added theory Glued_Codes.


Related publications

Session Combinatorics_Words_Graph_Lemma