Evaluating ASP and Commercial Solvers on the CSPLib

Abstract

This paper deals with four solvers for combinatorial problems: the commercial state-of-the-art solver ILOG oplstudio, and the research answer set programming (ASP) systems dlv, smodels and cmodels. The first goal of this research is to evaluate the relative performance of such systems when used in a purely declarative way, using a reproducible and extensible experimental methodology. In particular, we consider a third-party problem library, i.e., the CSPLib, and uniform rules for modelling and instance selection. The second goal is to analyze the marginal effects of popular reformulation techniques on the various solving technologies. In particular, we consider structural symmetry breaking, the adoption of global constraints, and the addition of auxiliary predicates. Finally, we evaluate, on a subset of the problems, the impact of numbers and arithmetic constraints on the different solving technologies. Results show that there is not a single solver winning on all problems, and that reformulation is almost always beneficial: symmetry-breaking may be a good choice, but its complexity has to be carefully chosen, by taking into account also the particular solver used. Global constraints often, but not always, help opl, and the addition of auxiliary predicates is usually worth, especially when dealing with ASP solvers. Moreover, interesting synergies among the various modelling techniques exist.

Compiling finite domain constraints to SAT withBEE

“…DNA word problem: Mancini et al (2008) provide a comparison of several stateof-the-art solvers applied to the DNA word problem with a variety of encoding techniques. Their best reported result is a solution with 87 DNA words, obtained in 554 seconds, using an OPL (van Hentenryck 1999) model with lexicographic order to break symmetry.…”

A Unifying Framework for Structural Properties of CSPs: Definitions, Complexity, Tractability

“…As the Factoring example shows, such problems arise frequently in practice, either as subproblems of other CSPs, as in presence of functional dependencies (cf. also Mancini, Cadoli, Micaletto, & Patrizi, 2008, for more examples), or because of intrinsic characteristics of the problem at hand. In general, if a problem has a unique solution, all variables have a determined value.…”

Optimal placement of valves in a water distribution network with CLP(FD)

“…One very promising approach would be to use Large Neighbourhood Search, that has been implemented in Prolog in previous works (Dal Palù et al 2010), A very interesting line of research would be to develop an Answer Set Program-ming model. ASP is often faster than CLP(FD) when the domains of the variables do not contain many values (Dovier et al 2005;Mancini et al 2008); we plan to develop an ASP application in the near future.…”