Use of production systems for modeling asynchronous, concurrent processes
Michael D. Zisman · ACM SIGART Bulletin · 1977
Because of the event-driven, nature of asynchronous, concurrent processes, production systems (PS's) are an attractive modeling tool. The system of interest can be modeled with a large number of independent states, with independent actions, and tile knowledge base can be conveniently encoded declaratively. However, asynchronous, concurrent processes normally have strict requirements for inter-process communication and coordination; this requires a substantial degree of inter-rule communication in the PS. The result of this is that a complex control structure is embedded in the short term memory (STM); this is generally considered unattractive for a number of reasons. This paper proposes a separate, explicit control structure for modeling asynchronous, concurrent processes With PS's. Specifically, the use of a Petri net is addressed. A system of asynchronous, concurrent processes can be modeled using 'PS's to model the individual processes or events and using a Petri net to model the relationships between the processes. Furthermore, a hierarchy of such networks is proposed; an allowable production rule action is the instantiation of another network. This is supported with a structured, hierarchial STM.