Zobrazeno 1 - 10
of 162
pro vyhledávání: '"Raftery, A. G."'
A representation theorem is proved for De Morgan monoids that are (i) semilinear, i.e., subdirect products of totally ordered algebras, and (ii) negatively generated, i.e., generated by lower bounds of the neutral element. Using this theorem, we prov
Externí odkaz:
http://arxiv.org/abs/2206.12461
For (finitary) deductive systems, we formulate a signature-independent abstraction of the \emph{weak excluded middle law} (WEML), which strengthens the existing general notion of an inconsistency lemma (IL). Of special interest is the case where a qu
Externí odkaz:
http://arxiv.org/abs/2108.09168
Publikováno v:
Algebra Universalis 82, 6 (2021)
A commutative residuated lattice A is said to be subidempotent if the lower bounds of its neutral element e are idempotent (in which case they naturally constitute a Brouwerian algebra A*). It is proved here that epimorphisms are surjective in a vari
Externí odkaz:
http://arxiv.org/abs/1902.05011
Autor:
Moraschini, T., Raftery, J. G.
It is proved that every prevariety of algebras is categorically equivalent to a "prevariety of logic", i.e., to the equivalent algebraic semantics of some sentential deductive system. This allows us to show that no nontrivial equation in the language
Externí odkaz:
http://arxiv.org/abs/1902.04160
A quasivariety K of algebras has the joint embedding property (JEP) iff it is generated by a single algebra A. It is structurally complete iff the free countably generated algebra in K can serve as A. A consequence of this demand, called "passive str
Externí odkaz:
http://arxiv.org/abs/1902.04159
Publikováno v:
Journal of Pure and Applied Algebra, Volume 223, Issue 7, 2019, Pages 2780-2803
It is proved that every finitely subdirectly irreducible De Morgan monoid A (with neutral element e) is either (i) a Sugihara chain in which e covers not(e) or (ii) the union of an interval subalgebra [not(a), a] and two chains of idempotents, (not(a
Externí odkaz:
http://arxiv.org/abs/1801.06650
Publikováno v:
Studia Logica 108, 255-275 (2020)
Generalizing a theorem of Campercholi, we characterize, in syntactic terms, the ranges of epimorphisms in an arbitrary class of similar first-order structures (as opposed to an elementary class). This allows us to strengthen a result of Isbell, as fo
Externí odkaz:
http://arxiv.org/abs/1801.06647
Publikováno v:
The Review of Symbolic Logic 13 (2020) 338-374
The variety DMM of De Morgan monoids has just four minimal subvarieties. The join-irreducible covers of these atoms in the subvariety lattice of DMM are investigated. One of the two atoms consisting of idempotent algebras has no such cover; the other
Externí odkaz:
http://arxiv.org/abs/1801.06654
Publikováno v:
Studia Logica: An International Journal for Symbolic Logic, 2020 Apr 01. 108(2), 255-275.
Externí odkaz:
https://www.jstor.org/stable/45379225
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