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pro vyhledávání: '"Raftery, J. G."'
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
Akademický článek
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Autor:
Raftery, J. G., Świrydowicz, K.
Publikováno v:
Studia Logica: An International Journal for Symbolic Logic, 2016 Jun 01. 104(3), 381-387.
Externí odkaz:
http://www.jstor.org/stable/24754974