INVESTIGATING PRODUCTION SYSTEM REPRESENTATIONS FOR NON-COMBINATORIALMATCH

Eliminating combinatorics from the match in production systems (or rul e-based systems) is important for expert systems, real-time performanc e, machine learning (particularly with respect to the utility issue), parallel implementations and cognitive modeling. In [74], the unique-a ttribute representation was introduced to eliminate combinatorics from the match. However, in so doing, unique-attributes engender a suffici ently negative set of trade-offs, so that investigating whether there are alternative representations that yield better trade-offs becomes o f critical importance. This article identifies two promising spaces of such alternatives, and explores a number of the alternatives within t hese spaces. The first space is generated from local syntactic restric tions on working memory. Within this space, unique-attributes is shown to be the best alternative possible. The second space comes from rest rictions on the search performed during the match of individual produc tions (match-search). In particular, this space is derived from the co mbination of a new, more relaxed, match formulation (instantiationless match) and a set of restrictions derived from the constraint-satisfac tion literature. Within this space, new alternatives are found that ou tperform unique-attributes in some, but not yet all, domains.