The amalgamation class of a discriminator variety is finitely axiomatizable

1983 ◽  
pp. 1-9 ◽  
Author(s):  
Clifford Bergman
Keyword(s):  
Discriminator Variety ◽  
Amalgamation Class

Every minimal dual discriminator variety is minimal as a quasivariety

2021 ◽  
Vol 82 (2) ◽  
Author(s):  
Xavier Caicedo ◽  
Miguel Campercholi ◽  
Keith A. Kearnes ◽  
Pedro Sánchez Terraf ◽  
Ágnes Szendrei ◽  
...  
Keyword(s):  
Discriminator Variety

Finitely generic models of TUH, for certain model companionable theories T

1985 ◽  
Vol 50 (3) ◽  
pp. 604-610
Author(s):  
Francoise Point
Keyword(s):  
Discriminator Variety ◽  
Generic Models ◽  
Elementary Class ◽  
Ordered Groups ◽  
Existentially Closed ◽  
Closed Element ◽  
Starting Point ◽  
Joint Embedding ◽  
Joint Embedding Property ◽  
Generic Elements

The starting point of this work was Saracino and Wood's description of the finitely generic abelian ordered groups [S-W].We generalize the result of Saracino and Wood to a class ∑UH of subdirect products of substructures of elements of a class ∑, which has some relationships with the discriminator variety V(∑t) generated by ∑. More precisely, let ∑ be an elementary class of L-algebras with theory T. Burris and Werner have shown that if ∑ has a model companion then the existentially closed models in the discriminator variety V(∑t) form an elementary class which they have axiomatized. In general it is not the case that the existentially closed elements of ∑UH form an elementary class. For instance, take for ∑ the class ∑0 of linearly ordered abelian groups (see [G-P]).We determine the finitely generic elements of ∑UH via the three following conditions on T:(1) There is an open L-formula which says in any element of ∑UH that the complement of equalizers do not overlap.(2) There is an existentially closed element of ∑UH which is an L-reduct of an element of V(∑t) and whose L-extensions respect the relationships between the complements of the equalizers.(3) For any models A, B of T, there exists a model C of TUH such that A and B embed in C.(Condition (3) is weaker then “T has the joint embedding property”. It is satisfied for example if every model of T has a one-element substructure. Condition (3) implies that ∑UH has the joint embedding property and therefore that the class of finitely generic elements of ∑UH is complete.)

Absolute Retracts and Amalgamation in Certain Congruence Distributive Varieties

1989 ◽  
Vol 32 (3) ◽  
pp. 309-313 ◽  
Author(s):  
Peter Jipsen ◽  
Henry Rose
Keyword(s):  
Direct Products ◽  
Distributive Variety ◽  
Absolute Retracts ◽  
Congruence Distributive Variety ◽  
Amalgamation Class ◽  
Congruence Distributive

AbstractIt is shown that if V is a congruence distributive variety whose members have one element subalgebras, then the class of absolute retracts of V is closed under direct products. If V is residually small, then a characterisation of the amalgamation class of V is given.

Filtral powers of structures

1998 ◽  
Vol 63 (4) ◽  
pp. 1239-1254 ◽  
Author(s):  
P. Ouwehand ◽  
H. Rose
Keyword(s):  
Elementary Substructure ◽  
Elementary Class ◽  
Reduced Products ◽  
Amalgamation Class ◽  
Finite Products

AbstractAmong the results of this paper are the following:1. Every Boolean (ultra)power is the union of an updirected elementary family of direct ultrapowers.2. Under certain conditions, a finitely iterated Boolean ultrapower is isomorphic to a single Boolean ultrapower.3. A ω-bounded filtral power is an elementary substructure of a filtral power.4. Let be an elementary class closed under updirected unions (e.g., if is an amalgamation class); then is closed under finite products if and only if is closed under reduced products if and only if is a Horn class.

Quasi-discriminator varieties

2014 ◽  
Vol 24 (03) ◽  
pp. 375-411 ◽  
Author(s):  
Francesco Paoli ◽  
Antonio Ledda ◽  
Tomasz Kowalski ◽  
Matthew Spinks
Keyword(s):  
Fuzzy Logic ◽  
General Concept ◽  
Discriminator Variety ◽  
Algebraic Characterization ◽  
Basic Properties ◽  
Discriminator Varieties ◽  
Lattice Of Subvarieties

We generalize the notion of discriminator variety in such a way as to capture several varieties of algebras arising mainly from fuzzy logic. After investigating the extent to which this more general concept retains the basic properties of discriminator varieties, we give both an equational and a purely algebraic characterization of quasi-discriminator varieties. Finally, we completely describe the lattice of subvarieties of the pure pointed quasi-discriminator variety, providing an explicit equational base for each of its members.

scholarly journals The Subquasivariety Lattice of a Discriminator Variety

2001 ◽  
Vol 159 (1) ◽  
pp. 18-50 ◽  
Author(s):  
Javier Blanco ◽  
Miguel Campercholi ◽  
Diego Vaggione
Keyword(s):  
Discriminator Variety

A discriminator variety of Gödel algebras with operators arising in quantum computation

2009 ◽  
Vol 160 (8) ◽  
pp. 1082-1098 ◽  
Author(s):  
Roberto Giuntini ◽  
Hector Freytes ◽  
Antonio Ledda ◽  
Francesco Paoli
Keyword(s):  
Quantum Computation ◽  
Discriminator Variety

A structure theorem for strongly abelian varieties with few models

1991 ◽  
Vol 56 (3) ◽  
pp. 832-852 ◽  
Author(s):  
Bradd Hart ◽  
Matthew Valeriote
Keyword(s):  
Abelian Variety ◽  
Structure Theorem ◽  
Structural Condition ◽  
Discriminator Variety ◽  
Complete Theory ◽  
Affine Variety ◽  
Finitely Generated ◽  
Locally Finite ◽  
Elementary Class ◽  
Definition Of

By a variety, we mean a class of structures in some language containing only function symbols which is equationally defined or equivalently is closed under homomorphisms, submodels and products.If K is a class of -structures then I(K, λ) denotes the number of nonisomorphic models in K of cardinality λ. When we say that K has few models, we mean that I(K,λ) < 2λ for some λ > ∣∣. If I(K,λ) = 2λ for all λ > ∣∣, then we say K has many models. In [9] and [10], Shelah has shown that for an elementary class K, having few models is a strong structural condition.Before we give the definition of strongly abelian, let us motivate how it arises in this context. A variety is locally finite if every finitely generated algebra in is finite. If and are subvarieties of then = ⊗ means that is the variety generated by and and moreover there is a term τ(x, y) so that τ(x, y) = x holds in and τ(x, y) = y holds in . is called the varietal product of and . As a consequence, if = ⊗ then for every M ∈ there is a unique (up to isomorphism) A ∈ and B ∈ so that M ≅ A × B.In [4], McKenzie and Valeriote proved the following theorem.Theorem 0.1. Ifis a locally finite decidable variety, then there are three subvarieties of, , and, so that = ⊗ ⊗ andis an affine variety, is a strongly abelian variety andis a discriminator variety.For the exact definitions of the terms affine and discriminator one can see [4]; however, for us here it is important to know that an affine variety is polynomially equivalent to a variety of left R-modules over some ring R and that any nontrivial discriminator variety contains an algebra whose complete theory is unstable.

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