Showing papers by "Irina Rish published in 1996"

To guess or to think? Hybrid algorithms for SAT (extended abstract)

Abstract: Complete algorithms for solving propositional satis ability fall into twomain classes: backtracking (e.g., the Davis-Putnam Procedure [4]) and resolution (e.g., Directional Resolution [9]). Roughly speaking, backtracking amounts to \guessing" (making assumption), while resolution invokes \thinking" (inference). Experimental results show that both \pure guessing" and \pure thinking" might be ine cient. We propose an approach that combines resolution and backtracking and yields a family of hybrid algorithms, parameterized by a bound on the "e ective" amount of resolution allowed. The idea is to divide the set of propositional variables into two classes: conditioning variables, which are assigned truth values, and resolution variables, which are resolved upon. We report on preliminary experimental results demonstrating that on certain classes of problems hybrid algorithms are more e ective than either the Davis-Putnam Procedure or Directional Resolution in isolation.