A Condition Equivalent to the Solvability of the Endomorphism Problem for Free Groups

Charles C. Edmunds
1979 Proceedings of the American Mathematical Society  
To solve the endomorphism problem for a word W involving n generators of a free group F, it suffices to solve the problem assuming that the images of W involve no more than n generators.
doi:10.2307/2042909 fatcat:vmyd535rajf5dbyug2sgb4axn4