Rectangularity
by
Emil W. Kiss
Eotvos University, Budapest, Hungary
Coauthors: K. A. Kearnes

The discovery of the centrality relation between congruences of general algebras lead to the development of such powerful tools as modular commutator theory and tame congruence theory. Ralph McKenzie introduced a modified version of this concept later, which evolved to another important relation among congruences, called rectangular centrality. Though less well-explored, and seemingly not so well behaved as ordinary centrality, this new concept has also proved to be useful in several applications, particularly when one tries to extend results beyond congruence modularity. Rectangularity has two variants, corresponding to the ``unary'' and ``semilattice'' type of tame congruence theory. The talk will introduce this concept, and present some of the applications.

Date received: May 24, 2000

Copyright © 2000 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caee-78.