Results 41 to 50 of about 81 (74)

Q-Universal Quasivarieties of Algebras

Proceedings of the American Mathematical Society, 1994
For any quasivariety \({\mathbf K}\) of algebras (of finite type), let \(L({\mathbf K})\) be the lattice of all quasivarieties in \({\mathbf K}\). Call \({\mathbf K}\) \(Q\)-universal iff for any quasivariety \({\mathbf M}\) (of algebras of finite type), \(L({\mathbf M})\) is a homomorphic image of a sublattice of \(L({\mathbf K})\).
Adams, M. E., Dziobiak, W.
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UNREASONABLE LATTICES OF QUASIVARIETIES

International Journal of Algebra and Computation, 2012
A quasivariety is a universal Horn class of algebraic structures containing the trivial structure. The set [Formula: see text] of all subquasivarieties of a quasivariety [Formula: see text] forms a complete lattice under inclusion. A lattice isomorphic to [Formula: see text] for some quasivariety [Formula: see text] is called a lattice of ...
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Quasivarieties of Metric Algebras

Algebra and Logic, 2003
The author introduces the concepts of a continuous family of quasi-identities and of a continuous quasivariety. For continuous quasivarieties, a characterization theorem and an analog of the Birkhoff theorem on subdirect decomposition are proven.
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Joins of minimal quasivarieties

Studia Logica, 1995
Let \({\mathcal D}_2\) denote the variety of algebras \((L;\wedge, \vee, 0, c_0, c_1,1)\) which are distributive \((0,1)\)-lattices with two distinguished elements \(c_0, c_1\in L\). It is known that the only subdirectly irreducible algebras in \({\mathcal D}_2\) are \(2_{ij}= (\{0, 1\};\wedge, \vee, 0, i,j, 1)\) with \(i,j\in \{0, 1\}\). Let, further,
Adams, M. E., Dziobiak, W.
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Quasivarieties of Cantor algebras

Algebra Universalis, 2001
A variety \(\mathcal V\) is minimal if it is equationally complete. A quasivariety is called \(Q\)-universal if for every quasivariety \(K\) of a finite type the lattice \(L_Q (K)\) of all subquasivarieties is a homomorphic image of \(L_Q (Q)\). The author studies varieties \(C_{mn}\) of the so-called Cantor algebras (firstly treated in the early 60s ...
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Quasivarieties of distributivep-algebras

Algebra Universalis, 1992
The paper exhibits three results on quasivarieties of (distributive) \(p\)- algebras: There exists a quasivariety \(\mathbb{K}\) of such algebras such that \(\mathbb{B}_ 2\subset\mathbb{K}\subset\mathbb{B}_ 4\), but neither \(\mathbb{K}\subseteq\mathbb{B}_ 3\) nor \(\mathbb{B}_ 3\subseteq\mathbb{K}\), where \(\mathbb{B}_ i\) denotes the \(i\)-th Lee ...
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SUBFUNCTORS ASSOCIATED WITH QUASIVARIETIES

1984
Quasivarieties of algebras are characterized as SP-classes closed under a certain construction of directed unions of congruences.
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Quasivariety of special jordan algebras

Algebra and Logic, 1983
It is well known that the class of all special Jordan algebras does not form a variety of algebras, but it is not difficult to see that this class forms a quasivariety of algebras. The natural question then arises whether this quasivariety can be defined by a finite number of quasi- identities.
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Quasivarieties of Graphs and Independent Axiomatizability

Siberian Advances in Mathematics, 2018
Summary: In the present article, we continue to study the complexity of the lattice of quasivarieties of graphs. For every quasivariety \(K\) of graphs that contains a non-bipartite graph, we find a subquasivariety \(K'\subset K\) such that there exist \(2^{\omega}\) subquasivarieties \(K'' \in L_q(K')\) without covers (hence, without independent bases
Kravchenko, A. V., Yakovlev, A. V.
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Quasivarieties of graphs

Siberian Mathematical Journal, 1994
By a graph we mean a model of a binary predicate \(\rho(x,y)\). Many well-known properties of binary relations, such as reflexivity, symmetry, antisymmetry, transitivity, etc., are written down by means of quasiidentities. Such important classes of graphs as the class of all partial orders, the class of models of an equivalence relation, the class of ...
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