A proof of Ehrenfeucht’s conjecture. (English) Zbl 0602.68066

Ehrenfeucht’s conjecture states that each subset S of a finitely generated free monoid has a finite subset T such that if two endomorphisms of the monoid agree on T, then they agree on S. It is the purpose of this note to verify the conjecture.


68Q45 Formal languages and automata
20M05 Free semigroups, generators and relations, word problems
20M35 Semigroups in automata theory, linguistics, etc.
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