In the paper we present completeness theorems for hybrid logics, discuss the problem of finite axiomatization and study term rewriting and unification for the variety of distributive lattices and theâ€¦ (More)

Derived varieties were invented by P. Cohn in [4]. Derived varieties of a given type were invented by the authors in [10]. In the paper we deal with the derived variety VÏƒ of a given variety, by aâ€¦ (More)

It is proved that if a nite non-trivial quasi-order is not a linear order then there exist 2 @ 0 clones, which consist of functions preserving the quasi-order and contain all unary functions withâ€¦ (More)

In [4] (see [2]) the notion of a hypersubstitution of a given type and the notion of a derived variety D(V ) of a given variety V of a fixed type Ï„ were invented. Suitable hyperequational calculusâ€¦ (More)

We invent the notion of a derived variety as a tool for exploring the lattice of subvarieties of a given variety. A modification of the notion of a fluid variety invented in [10] as a counterpart ofâ€¦ (More)