A NOTATION FOR DETERMINISTIC COOPERATING PROCESSES

This paper proposes extensions of sequential programming languages for parallel programming that have the following features: 1) Dynamic Str uctures: The process structure is dynamic, Processes and variables can be created and deleted. 2) Paradigm Integration: The programming nota tion supports shared memory and message passing models. 3) Determinism : Demonstrating that a program is deterministic-all executions with th e same input produce the same output-is straightforward. Programs can be written so that compilers can verify that the programs are determin istic. Nondeterministic constructs can be introduced in a sequence of refinement steps to obtain greater efficiency if required. The ideas h ave been incorporated in an extension of Fortran, but the underlying s equential imperative language is not central to the ideas described he re. A compiler for the Fortran extension, called Fortran M, is availab le by anonymous ftp from Argonne National Laboratory. Fortran M has be en used for a variety of parallel applications.