In [12] the study of Positive Modal Logic (PML) is initiated using standard Kripke semantics and the positive modal algebras (a class of bounded distributive lattices with modal operators) areâ€¦ (More)

logics can be studied as models of Gentzen systems (see [25]). In this<lb>context, we say that an abstract logic ã€ˆA,Cã€‰ is a model of a Gentzen system G<lb>when for any family of sequents<lb>{Î“i B Ï†iâ€¦ (More)

The present paper introduces and studies the variety WH of weakly Heyting algebras. It corresponds to the strict implication fragment of the normal modal logic K which is also known as theâ€¦ (More)

The paper contains some algebraic results on several varieties of algebras having an (interlaced) bilattice reduct. Some of these algebras have already been studied in the literature (for instanceâ€¦ (More)

A filter of a sentential logic S is Leibniz when it is the smallest one among all the S-filters on the same algebra having the same Leibniz congruence. This paper studies these filters and theâ€¦ (More)

We generalize Priestley duality for distributive lattices to a duality for distributive meet-semilattices. On the one hand, our generalized Priestley spaces are easier to work with than Celaniâ€™sâ€¦ (More)