Generalized Bruck-Reilly *-extension as a new example of a monoid with a non-finitely generated group of units

Abstract

We present a new example of a #8230;nitely presented monoid, namely Bruck-Reilly extension of generalized Bruck-Reilly *-extension of free group with in #8230;nite rank, the group of units of which is not #8230;nitely generated.We present a new example of a #8230;nitely presented monoid, namely Bruck-Reilly extension of generalized Bruck-Reilly *-extension of free group with in #8230;nite rank, the group of units of which is not #8230;nitely generated.