A look back and a look ahead.

Conflict-Directed Backjumping Revisited

In recent years, many improvements to backtracking algorithms for solving constraint satisfaction problems have been proposed. The techniques for improving backtracking algorithms can be conveniently classiied as look-ahead schemes and look-back schemes. Unfortunately , look-ahead and look-back schemes are not entirely orthogonal as it has been observed empirically that the enhancement of look-...

Connict-directed Backjumping Revisited

In recent years, many improvements to backtracking algorithms for solving constraint satisfaction problems have been proposed. The techniques for improving backtracking algorithms can be conveniently classi ed as look-ahead schemes and look-back schemes. Unfortunately, look-ahead and look-back schemes are not entirely orthogonal as it has been observed empirically that the enhancement of look-a...

Look-Ahead Versus Look-Back for Satisfiability Problems

CNF propositional satis ability SAT is a special kind of the more general Constraint Satisfaction Problem CSP While look back techniques appear to be of little use to solve hard random SAT problems it is supposed that they are necessary to solve hard structured SAT problems In this paper we propose a very simple DPL procedure called Satz which only employs some look ahead techniques a variable ...

Experimenting with Look-Back Heuristics for Hard ASP Programs

Competitive native solvers for Answer Set Programming (ASP) perform a backtracking search by assuming the truth of literals. The choice of literals (the heuristic) is fundamental for the performance of these systems. Most of the efficient ASP systems employ a heuristic based on look-ahead, that is, a literal is tentatively assumed and its heuristic value is based on its deterministic consequenc...

A look back, a look ahead.

Backtracking Algorithms for Constraint Satisfaction Problems { a Survey

Over the past twenty years, a number of backtracking algorithms for constraint satisfaction problems, have been developed. This survey describes the basic backtrack search within the search space framework and then presents a number of improvements including look-back methods such as backjumping, constraint recording, backmarking, and look-ahead methods such as, forward checking, and dynamic va...