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Extending Unit Propagation Look-Ahead of DPLL Procedure

Summary: Extending Unit Propagation Look-Ahead of
DPLL Procedure
Logic and Computation Program, Canberra Research Laboratory
National ICT Australia Limited
Locked Bag 8001, Canberra, ACT 2601, Australia
Abstract. The DPLL (Davis-Putnam-Logemann-Loveland) procedure
is one of the most effective methods for solving SAT problems. It is well
known that its efficiency depends on the choice of the branching rule. Dif-
ferent branching rules are proposed in the literature. Unit propagation
look-ahead (UPLA) branching rule was one of the main improvements
in the DPLL procedure (e.g.,[10]). The UPLA branching rule integrated
in satz SAT solver [10] performs a series of variable filtering process at
each node as a static variable filtering agency. In this paper we introduce
and experiment with dynamic variable filtering (DVF) based branching
rule which extends the UPLA heuristic process for doing more filtering
and choosing a best branching variable from an irreducible sub-formula.
To enhance the performance of DVF branching rule, we integrate neigh-
borhood variable ordering heuristic (NVO) for exploring only the neigh-


Source: Anbulagan, A. - National ICT Australia & Computer Sciences Laboratory, Australian National University


Collections: Computer Technologies and Information Sciences