Design and distributed implementation of parallel logic language Shared Prolog.

The parallel logic language Shared Prolog embeds Prolog as its sequential component. A program is Shared Prolog is composed of a set of logic agents, i.e. Prolog programs, that communicate associatively via a shared workspace called blackboard. The distinct features that characterize Shared Prolog with respect to other parallel (logic) languages are: scheduling of agents and granularity of parallelism explicitly controlled; Prolog embedded in the language; intrinsic modularity; associative send/receive of messages among agents with a simple operational semantics in terms of assert/retract of clauses. The model of communication puts Shared Prolog in the Linda family of parallel languages. The current prototype implementation is exposed. The architecture of the system is a distributed network of extended Prolog interpreters running under Unix and communicating via Internet sockets, and was obtained refining a specification written in SP itself.