50 citations · 146 across the 25 of their papers we have counts for
Showing math.GRShow all
3 papers · 1 filter
math.GR2019
Recognizing pro-R closures of regular languages
Jorge Almeida, José Carlos Costa, Marc Zeitoun
Given a regular language L, we effectively construct a unary semigroup that recognizes the topological closure of L in the free unary semigroup relative to the variety of unary sem…
math.GR2015★ 5 cited
Reducibility of pointlike problems
J. Almeida, J. C. Costa, M. Zeitoun
We show that the pointlike and the idempotent pointlike problems are reducible with respect to natural signatures in the following cases: the pseudovariety of all finite semigroups…
math.GR2015★ 1 cited
Factoriality and the Pin-Reutenauer procedure
J. Almeida, J. C. Costa, M. Zeitoun
We consider implicit signatures over finite semigroups determined by sets of pseudonatural numbers. We prove that, under relatively simple hypotheses on a pseudovariety V of semigr…