Automated Reasoning: Recent Papers

Johann Schumann

SiCoTHEO
Simple Competitive parallel Theorem Provers based on SETHEO

Proc. of PPAI'95, Montreal, Ca., 1995.

Abstract

In this paper, we present SiCoTHEO, a zoo of parallel theorem provers for first order predicate logic. They are based on the sequential prover SETHEO. Parallelism is exploited by competition: on each processor, an identical copy of SETHEO tries to prove the entire formula. However, certain parameters which influence SETHEO's behavior are set differently for each processor. As soon as one processor finds a proof, the entire system is stopped. Three different versions of SiCoTHEO are presented in this paper. We have used competition on completeness mode (parallel iterative deepening, SiCoTHEO-PID) and completeness bounds (parameterized combination of completeness bounds, SiCoTHEO-CBC), and on the search mode (top-down combined with bottom-up, SiCoTHEO-DELTA). The experimental results were obtained with a prototypical implementation, running on a network of workstations. This parallel model is fault-tolerant and does not need communication during run-time (except start and stop message). We found that only little efficiency is gained for SiCoTHEO-PID, which reaches peak performance with only 4 processors. SiCoTHEO-CBC and SiCoTHEO-DELTA, however, showed significant speed-up, and improved performance up to the 50 processors used.

BibTeX-entry or PostScript