Since production systems were first proposed in 1943 as a general

computational mechanism, the methodology has seen a great deal of

development and has been applied to a diverse collection of problems.

Despite the wide scope of goals and perspectives demonstrated by the

various systems, there appear to be many recurrent themes. This

paper is an attempt to provide an analysis and overview of those

themes, as well as a conceptual framework by which many of the

seemingly disparate efforts can be viewed, both in relation to each

other, and to other methodologies.

Accordingly, we use the term 'production system' in a broad sense,

and attempt to show how most systems which have used the term can be

fit into the framework. The comparison to other methodologies is

intended to provide a view of PS characteristics in a broader

context, with primary reference to procedurally-based techniques, but

with reference also to some of the current developments in

programming and the organization of data and knowledge bases.

This is a slightly revised version of a paper to appear in %2Machine

Representations of Knowledge%*, Dordrecht, D. Reidel Publishing

Company (1976).