2023/11/05 by Ascari, Dario
#20E05 #20E07 (Primary) 20F65 (Secondary) #FOS: Mathematics #Group Theory (math.GR)
paper · doi:10.48550/arxiv.2311.02784
We provide an algorithm that, given a finite set of generators for a subgroup H of a finitely generated free group F, determines whether H is echelon or not and, in case of affirmative answer, also computes a basis with respect to which H is in echelon form. This answers to a question of A. Rosenmann. We also prove, by means of a counterexample, that intersection of two echelon subgroups needs not to be echelon, answering to another question of A. Rosenmann.