77 citations · 154 across the 22 of their papers we have counts for
5 papers · 1 filter
On the insertion of n-powers
J. Almeida, O. Klíma
In algebraic terms, the insertion of -powers in words may be modelled at the language level by considering the pseudovariety of ordered monoids defined by the inequality $1\le x…
Towards a pseudoequational proof theory
Jorge Almeida, Ondřej Klíma
A new scheme for proving pseudoidentities from a given set Σ of pseudoidentities, which is clearly sound, is also shown to be complete in many instances, such as when Σ defines a l…
Nilpotency and strong nilpotency for finite semigroups
J. Almeida, M. Kufleitner, M. H. Shahzamanian
Nilpotent semigroups in the sense of Mal'cev are defined by semigroup identities. Finite nilpotent semigroups constitute a pseudovariety, , which has finite rank. The…
The linear nature of pseudowords
Jorge Almeida, Alfredo Costa, José Carlos Costa +1
Given a pseudoword over suitable pseudovarieties, we associate to it a labeled linear order determined by the factorizations of the pseudoword. We show that, in the case of the pse…
Commutative positive varieties of languages
Jorge Almeida, Zoltán Ésik, Jean-Éric Pin
We study the commutative positive varieties of languages closed under various operations: shuffle, renaming and product over one-letter alphabets.