Several categorical relationships (adjunctions) between models for concurrency have been established, allowing the translation of concepts and properties from one model to another. A central example is a coreflection between Petri nets and asynchronous transition systems. The purpose of the present paper is to illustrate the use of such relationships by transferring to Petri nets a general conc...

Let X be a Tychonoff space and A a subalgebra of C(X) containing C∗(X). Suppose that CK(X) is the set of all functions in C(X) with compact support. Kohls has shown that CK(X) is precisely the intersection of all the free ideals in C(X) or in C∗(X). In this paper we have proved the validity of this result for the algebra A. Gillman and Jerison have proved that for a realcompact space X, CK(X) i...

Given a metric space X we characterize those Y so that the realcompactification of X×Y is just the product of X with the realcompactification of Y . Examples are constructed to illustrate that the properties involved do depend on the metric spaces

semi-regular locales are extensions of the classical semiregularspaces. we investigate the conditions such that semi-regularizationis a functor. we also investigate the conditions such that semi-regularizationis a reflection or coreflection.