A Comparative Study of Models of Parallel Computation

In recent years, a large number of models of parallel computation have been proposed. These models have rather diverse motivations including problems from operating systems, hardware, numerical algorithms and others. In a recent thesis, Petersonl has proved that most of these models are equivalent in the sense that they generate the same set of "computations." This no­ tion of equivalence, which is a straightforward gener­ alization of the notion of equivalence of grammars in automata. theory, is rather unsatisfactory in that it does not distinguish among models that intuitively are not equivalent.