We study the approximability of 1-in-kSAT, the variant of Max kSAT where a clause is deemed satisfied when precisely one of its literals is satisfied. We also investigate different special cases of the problem, including those obtained by restricting the literals to be unnegated and/or all clauses to have size exactly k. Our results show that the 1in-kSAT problem exhibits some rather peculiar p...

Selecting and arranging parts is the core of a conngu-ration task. The validity of a connguration is deened in terms of constraints. Highly declarative, domain independent and simple to use, the constraint satisfaction problem (CSP) paradigm ooers an adequate framework for this task. However, the basic paradigm is not powerful enough to capture or to take advantage of essential aspects of conng...

In this paper, we present a dynamic and adaptive variable ordering heuristic which guides systematic search toward inconsistent or hard parts of a Constraint Satisfaction Problem (CSP). This generic heuristic is able to exploit information about previous states of the search process whereas traditional dynamic ones only exploit information about the current state. Intuitively, it avoids some tr...

The lexical choice process should be regarded as a constraint satisfaction problem: the generation system must choose a lexical unit that is accurate (t~mthful), va//d (conveys the necessary information), and preferred (maxirnal under a preference function). This corts~aint-based architecture allows a clema separation to be made between what the system knows of the object or event, and what the...

We study homomorphisms between randomly directed paths and give estimates on the probability of the existence of such homomorphism. We show that a random path is a core with positive probability. We apply our results in the investigation of homomorphism dualities, the most natural situation when a homomorphism (or Constraint Satisfaction) problem is in coNP.

Temporal information in the real world is often presented in an incomplete fashion. In this paper we propose a constraint-based calendar system suitable for inferring implicit calendric information. Our approach views calendars as constraint satisfaction problems, and time points are represented as instantiations of temporal units. We also present a semantic model for the system to justify the ...

We introduce a novel and exciting research area: symmetrising levels of consistency to produce stronger forms of consistency and more efficient mechanisms for establishing them. We propose new levels of consistency for Constraint Satisfaction Problems (CSPs) incorporating the symmetry group of a CSP. We first define Sym(i, j)-consistency, show that even Sym(1,0)-consistency can prune usefully, ...

Solver + AbstractSolver(problem : Problem) 1..n

When a Constraint Satisfaction Problem (CSP) admits no solution, it can be useful to pinpoint which constraints are actually contradicting one another and make the problem infeasible. In this paper, a recent heuristic-based approach to compute infeasible minimal subparts of discrete CSPs, also called Minimally Unsatisfiable Cores (MUCs), is improved. The approach is based on the heuristic explo...

The traditional approach for solving Constraint satisfaction Problems (CSPs) is searching the Assignment Space in which each state represents an assignment to some variables. This paper suggests a new search space formalization for CSPs, the Partial Domain Search Tree (PDST). In each PDST node a unique subset of the original domain is considered, values are excluded from the domains in each nod...