Some results about wRRA
Ian Hodkinson

A classical representation of a relation algebra is one that respects 
all boolean operations and the relational operations as well.  
The class RRA of relation algebras having a classical representation 
is quite well covered in the literature.  Most of its known properties 
are 'negative', but it is known to be a canonical variety.  In contrast, 
the class wRRA of relation algebras having a weak representation --- 
one that need not respect join or complement, though it must respect meet --- 
is less well understood.  It was introduced by Jonsson in 1959, 
but only recently shown (by B. Pecsi, 2009) to be a variety.   
Some other results about wRRA have been proved in the past few years, 
and in recent joint work with S. Mikulas and also involving R. Goldblatt 
and Y. Venema, we have shown it not to be canonical.  
The talk will discuss this material.