Results 1 to 10 of about 67 (62)
Existentially prime Jonsson quasivarieties and their Jonsson spectra [PDF]
Қарағанды университетінің хабаршысы. Математика сериясы, 2022 This article is devoted to the study of Jonsson quasivarieties in a signature enriched with new predicate and constant symbols. New concepts of semantic Jonsson quasivariety and fragment-conservativeness of the center of the Jonsson theory are ...
A.R. Yeshkeyev +2 more
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On Jonsson varieties and quasivarieties [PDF]
Қарағанды университетінің хабаршысы. Математика сериясы, 2021 In this paper, new objects of research are identified, both from the standpoint of model theory and from the standpoint of universal algebra.
A.R. Yeshkeyev
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Some non-standard quasivarieties of lattices [PDF]
Қарағанды университетінің хабаршысы. Математика сериясы, 2023 The questions of the standardness of quasivarieties have been investigated by many authors. The problem "Which finite lattices generate a standard topological prevariety?" was suggested by D.M. Clark, B.A. Davey, M.G. Jackson and J.G.
S.M. Lutsak +3 more
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On quasi-identities of finite modular lattices. II [PDF]
Қарағанды университетінің хабаршысы. Математика сериясы, 2023 The existence of a finite identity basis for any finite lattice was established by R. McKenzie in 1970, but the analogous statement for quasi-identities is incorrect.
A.O. Basheyeva, S.M. Lutsak
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On categoricity questions for universal unars and undirected graphs under semantic Jonsson quasivariety [PDF]
Қарағанды университетінің хабаршысы. Математика сериясы, 2023 The article is devoted to the study of semantic Jonsson quasivarieties of universal unars and undirected graphs. The first section of the article consists of basic necessary concepts from Jonsson model theory.
A.R. Yeshkeyev +2 more
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Structure of Quasivariety Lattices. IV. Nonstandard Quasivarieties
Siberian Mathematical Journal, 2021 Let \(\sigma\) be a finite signature and let \(\mathcal M\) be a quasivariety of signature \(\sigma\). According to Definition 4 of the paper, a class \(\mathcal A=\{\mathbb A_X\;|\;X\in {\mathcal P}_{\textrm{fin}}(\omega)\}\subseteq {\mathcal M}\) of finite \(\sigma\)-structures is called a \textit{finite \(B\)-class} with respect to \(\mathcal M\) if
Kravchenko, A. V. +2 more
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Admissibility in Finitely Generated Quasivarieties [PDF]
Logical Methods in Computer Science, 2013 Checking the admissibility of quasiequations in a finitely generated (i.e., generated by a finite set of finite algebras) quasivariety Q amounts to checking validity in a suitable finite free algebra of the quasivariety, and is therefore decidable ...
George Metcalfe +1 more
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Acta Scientiarum Mathematicarum, 2020 15 ...
Lehtonen, Erkko, Pöschel, Reinhard
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The inconsistency predicate on De Morgan lattices
Acta Universitatis Carolinae: Philosophica et Historica, 2017 We consider expansions of De Morgan lattices by an additional unary predicate interpreted in each De Morgan lattice by the ideal generated by all elements of the form a ∧ −a, and describe the finite lattice of strict universal Horn classes of such ...
Adam Přenosil
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Algebraic Theories of Quasivarieties
Journal of Algebra, 1998 By the theory of a locally finitely presentable category \(\mathcal K\) is meant the dual \(\text{Th}(\mathcal K)\) of the subcategory of finitely presentable objects. The authors characterize the theories of (many-sorted, finitary) (a) quasivarieties and (b) Horn classes.
Adámek, Jiřı́, Porst, Hans-E
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