Results 11 to 20 of about 302 (48)

Complete reducibility of pseudovarieties [PDF]

, 2007
The notion of reducibility for a pseudovariety has been introduced as an abstract property which may be used to prove decidability results for various pseudovariety constructions.
Almeida, Jorge, Costa, José Carlos, Zeitoun, Marc   +2 more
core   +1 more source

Free profinite R-trivial, locally idempotent and locally commutative semigroups [PDF]

, 1999
This paper is concerned with the structure of implicit operations on R intersection with LJ1, the pseudovariety of all R-trivial, locally idempotent and locally commutative semigroups.
A. Azevedo, A. Azevedo, C. Selmi, J. Almeida, J. Almeida, J. Almeida, J. Almeida, J. Almeida, J. Brzozowski, J. Reiterman, J.-E. Pin, J.-E. Pin, José Carlos Costa, L. Simon, M. Zeitoun, P. Weil, R. McNaughton, S. Eilenberg, Y. Zalcstein   +18 more
core   +1 more source

Some operators that preserve the locality of a pseudovariety of semigroups

, 2013
It is shown that if V is a local monoidal pseudovariety of semigroups, then K(m)V, D(m)V and LI(m)V are local. Other operators of the form Z(m)(_) are considered.
ALFREDO COSTA, Almeida J., ANA ESCADA, Eilenberg S., Kad'ourek J., Knast R.   +5 more
core   +1 more source

On the insertion of n-powers

, 2019
In algebraic terms, the insertion of $n$-powers in words may be modelled at the language level by considering the pseudovariety of ordered monoids defined by the inequality $1\le x^n$.
Almeida, J., Klíma, O.
core   +1 more source

On Varieties of Automata Enriched with an Algebraic Structure (Extended Abstract)

, 2014
Eilenberg correspondence, based on the concept of syntactic monoids, relates varieties of regular languages with pseudovarieties of finite monoids.
Klíma, Ondřej
core   +2 more sources

Some pseudovariety joins involving locally trivial semigroups and groups [PDF]

, 2001
In this paper, we present the computation of some pseudovariety joins of the form LI v H v V where LI is the pseudovariety of locally trivial semigroups and H is any pseudovariety of groups.
Costa, José Carlos
core   +1 more source

Three examples of join computations [PDF]

, 1997
This article answers three questions of J. Almeida. Using combinatorial, algebraic and topological methods, we compute joins involving the pseudovariety of finite groups, the pseudovariety of semigroups in which each idempotent is a right zero and the ...
Azevedo, Assis, Zeitoun, Marc
core   +2 more sources

On FO2 quantifier alternation over words

, 2009
We show that each level of the quantifier alternation hierarchy within FO^2[
H. Straubing, J. Almeida, J.-É. Pin, J.-É. Pin, J.-É. Pin, M. Adler, N. Immerman, P. Tesson, P. Tesson, P. Trotter, P. Weis, T. Schwentick, V. Diekert, W. Thomas   +13 more
core   +2 more sources

The FO^2 alternation hierarchy is decidable [PDF]

, 2012
We consider the two-variable fragment FO^2[
Kufleitner, Manfred, Weil, Pascal
core   +5 more sources

Varieties of Restriction Semigroups and Varieties of Categories [PDF]

, 2017
The variety of restriction semigroups may be most simply described as that generated from inverse semigroups (S, ·, −1) by forgetting the inverse operation and retaining the two operations x+ = xx−1 and x* = x−1x.
Jones, Peter
core   +1 more source