Contractions in Comparing Concurrency Semantics

We define for a simple concurrent rmperat~ve language both operational and denotat~onal semantic models as fixed points of contractions on complete metnc spaces. Next, we develop a general method for comparing different semantic models by relating their defining contractions and exploit-ing the fact that contractions have a unique fixed point. We present a study of a simple concurrent imperative language, called L0. We shall define an operational semantics 0o and a denotational semantics ®o for it and give a comparison of the two models. (We shall use the terms semantics and semantic model as synonyms.) This comparison is the main subject of our paper, rather than the specific nature of the language itself or th