# Algebra Seminar talk

2009-03-06

Toby **Kenney***Graphical Algebras - A new approach to Congruence Lattices*

Abstract:

In 1970, H. Werner gave a characterisation of which sublattices of a
partition lattice were actually the congruences of an algebra on the
underlying set. In his classification, he gave a new operation on
partition lattices, called graphical composition of relations. We consider
the question of which lattices with a notion of graphical composition can
be represented as congruence lattices, with graphical composition of
relations as in Werner.