## RESUMO / ABSTRACT

16 Dezembro 1997, 15:30

**Walter Tholen**, York University

*An axiomatic setting for separation and compactness*

Depending on a class of 'closed' morphisms, there are natural categorical
notions of separation and compactness, which have been studied intensively
in particular when 'closed' means 'closed with respect to a closure operator'.
In this talk we present a system of more general axioms on a class of 'closed'
morphisms, which still allow us to establish a satisfactory finite theory of
separation, compactness and perfectness, and to present a number of new
examples in topology and algebra. We shall also comment on Diers' Zariski
closure of algebraic sets in our context..