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Summary: What is a State of a System? (an outline)
Uri Abraham
Department of mathematics and computer science
Ben-Gurion University, Be'er Sheva, ISRAEL.
Abstract
We try to answer this question in de ning a state as a kind of a
pomset. The notion of a pomset is extended by adding to the unary
predicates unary functions of bounded depth. We show the equivalence
of two approaches to modeling concurrency: the sequential point of
view (which is based on states) and the partial-order point of view
(based on events). This note points to a possible approach for de ning
the semantics of communicating processes. We de ne and show how
to work with a natural subclass of information systems, which were
introduced by Scott to give denotational domains.
1 Preface
For sequential processes, a state is simply the complete information on all
the variables and control positions at a particular instant. For concurrent
communicating processes, the notion state has no such simple de nition,
unless severe limitations on concurrency are imposed. Considering its central
place, it is surprising that the general notion state has received so little
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