3 citations · 4 across the 5 of their papers we have counts for
6 papers · 1 filter
Structural completeness in quasivarieties
Paolo Aglianó, Alex CItkin
In this paper we study various forms of (hereditary) structural completeness for quasivarieties of algebras, using mostly algebraic techniques. More specifically we study relative…
Hereditarily Structurally Complete Superintuitionistic Deductive Systems
Alex Citkin
The paper studies hereditarily complete superintuitionistic deductive systems, that is, the deductive system which logic is an extension of the intuitionistic propositional logic.…
Admissibility in Positive Logics
Alex Citkin
The paper studies admissibility of multiple-conclusion rules in the positive logics. Using modification of a method used by M.~Wajsberg in the proof of the separation theorem, it i…
Lindenbaum method (propositional language)
Alex Citkin, Alexei Muravitsky
Lindenbaum method is named after the Polish logician Adolf Lindenbaum who prematurely and without a clear trace disappeared in the turmoil of the Second World War at the age of abo…
Characteristic Formulas 50 Years Later (An Algebraic Account)
Alex Citkin
The Jankov (characteristic) formulas were introduced by V.Jankov fifty tears ago in 1963. Nowadays the Jankov (or frame) formulas are used in virtually every branch of propositiona…
Ł-Axiomatizability in intermediate and normal modal logics
Alex Citkin
A set of formulas is complete relative to a given class of logics, if every logic from this class can be axiomatized by formulas from . A set of formulas is Ł-complete r…