2 citations · 3 across the 14 of their papers we have counts for
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Uncountably many maximally consistent neighborhood complete congruential modal logics
Zalán Gyenis, Krzysztof Krawczyk
We solve an open problem posed by Peter Fritz in \cite{Fritz} by proving that there are uncountably many C-Post complete congruential modal logics which are neighborhood complete.…
Two questions of Kowalski-Słomczyńska
Zalán Gyenis
That the inclusion is proper and Mod is not generated by free -algebras is proved, answering two open questions from Kowals…
More on modal logics and deduction
Zalán Gyenis, Zalán Molnár, Övge Öztürk
We study the relation between additivity and deduction theorems in the algebraic semantics of congruential modal logic. Additivity of the modal operator is well-known to imply the…
On covers of quasivarieties of p-algebras
Zalán Gyenis
This paper characterizes the covers of varieties of p-algebras in the lattice of quasivarieties of p-algebras. In particular, it is shown that every such variety has exactly one co…
Probabilities are always axiomatizable
Zalán Gyenis
In this paper we study the interaction between logic and probability. In particular, we show that the convex hull of evaluations of a broad class of logics is always effectively ax…
Permutations, substitutions and finite axiomatizability
Hajnal Andréka, Zalán Gyenis, István Németi
Algebras of relations form an algebraic framework for the study of logical systems, extending the correspondence between Boolean algebras and propositional logic. Tarski's represen…
Substitutions of variables are finitely axiomatizable over quantifications and permutations
Hajnal Andréka, Zalán Gyenis, István Németi
This paper proves that the equational theory of the class of representable polyadic algebras is finitely axiomatizable over its substitution-free reduct , f…
Varieties of modal algebras without the congruence extension property
Zalán Gyenis, Zalán Molnár
In a recent paper, Krawczyk proved that there are continuum many axiomatic extensions of global consequence associated with the modal system that do not admit the local deducti…
Chromatic number of the product of graphs, graph homomorphisms, Antichains and cofinal subsets of posets without AC
Amitayu Banerjee, Zalán Gyenis
We have observations concerning the set theoretic strength of the following combinatorial statements without the axiom of choice. 1. If in a partially ordered set, all chains are f…
Ultraproducts of continuous posets
H. Andréka, Z. Gyenis, I. Németi
It is known that nontrivial ultraproducts of complete partially ordered sets (posets) are almost never complete. We show that complete additivity of functions is preserved in ultra…