The problem of finding a semantic strategy for focusing inference rules

This article is the fifteenth of a series of articles discussing various open research problems in automated reasoning. Here we focus on finding a strategy — other than a simple syntactic one — that can be used for focusing the attention of the inference rule(s) in use. The problem proposed for research asks one to find semantic criteria for selecting the clauses needed to complete the application of an inference rule. Suggestions for test problems are included. We note that Yuan Yu has solved two of these problems using a rather different approach with the Boyer-Moore theorem prover; his work is reported elsewhere in this issue of the Journal of Automated Reasoning.This work was supported by the Applied Mathematical Sciences subprogram of the Office of Energy Research, U.S. Department of Energy, under Contract W-31-109-Eng-38.