Semantics of parallel program graphs

A denotational model for networks of parallel processes is presented which generalizes the work of Kahn by using alternative data types, e.g. Lisp-like operators on trees. It is shown that the ordering aspect of data types plays a central role in determining how much parallelism can be present. It is also shown that this model allows an implementation independent view of concepts related to the suspensions of Friedman and Wise and the lazy evaluator of Henderson and Morris. Finally, the cyclic structures of Kahn are shown to be eliminable through the use of recursion.