On a characterization of the lattice of subsystems of a transition system.
On a class of groupoids
On a class of subdirectly irreducible groupoids
On a power of relational structures
On a problem of B. Zelinka
On a problem of B. Zelinka, II
On a simple one-element extension of left zero semigroups
On algebraic lattices and semisimple algebras
On Algebras all of Whose Subalgebras are Simple; Some Solutions of Plonka's Problem
On bounding congruences in some algebras having the lattice structure
On central relations of complete lattices
On classes of algebraic systems closed with respect to quotients
On congruence lattices of finite partial unary algebras
On congruence lattices of regular semigroups with Q-inverse transversals.
On congruence relations of monounary algebras. I
On congruence relations of monounary algebras. II
On congruences in direct sums of algebras
On congruences of -sets
We describe -sets whose congruences satisfy some natural lattice or multiplicative restrictions. In particular, we determine -sets with distributive, arguesian, modular, upper or lower semimodular congruence lattice as well as congruence -permutable -sets for .
On congruences of ...x-normal semigroups.
On connections between hypergraphs and algebras
The aim of the present paper is to translate some algebraic concepts to hypergraphs. Thus we obtain a new language, very useful in the investigation of subalgebra lattices of partial, and also total, algebras. In this paper we solve three such problems on subalgebra lattices, other will be solved in [[Pio4]]. First, we show that for two arbitrary partial algebras, if their directed hypergraphs are isomorphic, then their weak, relative and strong subalgebra lattices are isomorphic. Secondly, we prove...