Results 1 to 10 of about 302 (48)
Free profinite semigroups over some classes of semigroups locally in DG [PDF]
International journal of algebra and computation, 2000 This paper is concerned with the structure of semigroups of implicit operations on various subpseudovarieties V of DReG intersection with LDG, where DReG and DG are the pseudovarieties of all semigroups S in which each regular D-class is, respectively, a
Costa, José Carlos
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E-varieties and E-pseudovarieties of regular semigroups [PDF]
Bulletin of the Australian Mathematical Society, 1996 zbMATH Open Web Interface contents unavailable due to conflicting licenses.
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Eilenberg Theorems for Free [PDF]
, 2017 Eilenberg-type correspondences, relating varieties of languages (e.g. of finite words, infinite words, or trees) to pseudovarieties of finite algebras, form the backbone of algebraic language theory.
Adámek, Jiří +3 more
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Theorems of Birkhoff type in pseudovarieties and e-varieties of regular semigroups [PDF]
Bulletin of the Australian Mathematical Society, 1999 zbMATH Open Web Interface contents unavailable due to conflicting licenses.
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Logic Meets Algebra: the Case of Regular Languages [PDF]
, 2007 The study of finite automata and regular languages is a privileged meeting point of algebra and logic. Since the work of Buchi, regular languages have been classified according to their descriptive complexity, i.e.
Denis Thérien +2 more
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The omega-inequality problem for concatenation hierarchies of star-free languages [PDF]
, 2017 The problem considered in this paper is whether an inequality of omega-terms is valid in a given level of a concatenation hierarchy of star-free languages.
Almeida, J., Klíma, O., Kunc, M.
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Equidivisible pseudovarieties of semigroups [PDF]
, 2016 We give a complete characterization of pseudovarieties of semigroups whose finitely generated relatively free profinite semigroups are equidivisible. Besides the pseudovarieties of completely simple semigroups, they are precisely the pseudovarieties that
Almeida, Jorge, Costa, Alfredo
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A Fibrational Approach to Automata Theory [PDF]
, 2015 For predual categories C and D we establish isomorphisms between opfibrations representing local varieties of languages in C, local pseudovarieties of D-monoids, and finitely generated profinite D-monoids.
Chen, Liang-Ting, Urbat, Henning
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An effective characterization of the alternation hierarchy in two-variable logic [PDF]
, 2012 We characterize the languages in the individual levels of the quantifier alternation hierarchy of first-order logic with two variables by identities. This implies decidability of the individual levels. More generally we show that the two-sided semidirect
Krebs, Andreas, Straubing, Howard
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Pointlike reducibility of pseudovarieties of the form V*D [PDF]
, 2016 In this paper, we investigate the reducibility property of semidirect products of the form V *D relatively to (pointlike) systems of equations of the form x1 =...= xn, where D denotes the pseudovariety of definite semigroups.
Almeida J. +4 more
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