Showing math.GRShow all
2 papers · 1 filter
math.GR2017
On the semigroup rank of a group
Mário J. J. Branco, Gracinda M. S. Gomes, Pedro V. Silva
For an arbitrary group , it is shown that either the semigroup rank equals the group rank , or . This is the starting point f…
math.GR2015
Takahasi semigroups
Mário J. J. Branco, Gracinda M. S. Gomes, Pedro V. Silva
Takahasi's theorem on chains of subgroups of bounded rank in a free group is generalized to several classes of semigroups. As an application, it is proved that the subsemigroups of…