A formalism for describing non-sequential processes

Abstract

In the paper a formalism is suggested for describing non-sequential processes. Processes are defined in this formalism by finite sets of rules. Such sets, called algorithms, consist of rules which indicate how relations between occurring objects may change (in general concurrently). They constitute a language of algorithms. Mathematical semantics of two types are formulated for this language. Ones, called objective, give descriptions of executions of algorithms in terms of objects which really exist in these executions. Other, called subjective, offer descriptions from the point of view of an observer. It is shown that objective semantics can be modelled in subjective ones.