Let be an MS-algebra with congruence permutable skeleton. We prove that solving a system of congruences in can be reduced to solving the restriction of the system to the skeleton of , plus solving the restrictions of the system to the intervals
Let denote the variety of lattices generated by convex sublattices of lattices in . For any proper variety , the variety is proper. There are uncountably many varieties with .
0. Introduction. Besides being of intrinsic interest, cylindric (semi-) lattices arise naturally from the study of dependencies in relational databases; the polynomials on a cylindric semilattice are closely related to the queries obtainable from project-join mappings on a relational database (cf. [D] for references). This note is intended to initiate the study of these structures, and only a few, rather basic results will be given. Some problems at the end will hopefully stimulate further research....
Pseudo BL-algebras are a noncommutative extention of BL-algebras. In this paper we study good pseudo BL-algebras and consider some classes of these algebras.
In this paper, we establish a theorem on Möbius inversion over power set lattices which strongly generalizes an early result of Whitney on graph colouring.