This paper presents a hybrid metaheuristic for solving the lot streaming problem in job shop production systems. In contrast with conventional tabu search implementations, where the disjunctive graph is adopted to represent the scheduling problem, our tabu search approach is based on permutation with repetition. Moreover, a specific procedure inspired by genetic algorithms is incorporated to se...

We show that for any graph G, by considering “activation” through the strong product with another graph H , the relation αpGq ď θpGq between the independence number and the Lovász number of G can be made arbitrarily tight: Precisely, the inequality αpG ˆHq ď θpGˆHq “ θpGqθpHq becomes asymptotically an equality for a suitable sequence of ancillary graphs H . This motivates us to look for other p...

A disjunctive temporal logic programming language, called Disjunctive Chronolog is presented in this paper. Disjunctive Chronolog combines the ideas of both temporal logic programming and disjunctive logic programming. The new language is capable of expressing dynamic behaviour as well as uncertainty, two notions that are very common in a variety of real systems. Minimal model semantics, model ...

Since most graphs evolve over time, it is useful to be able to query their history. We consider historical reachability queries that ask for the existence of a path in some time interval in the past, either in the whole duration of the interval (conjunctive queries), or in at least one time instant in the interval (disjunctive queries). We study both alternatives of storing the full transitive ...

Nowadays, many real problems can be modelled as Constraint Satisfaction Problems (CSPs). Some CSPs are considered non-binary disjunctive CSPs. Many researchers study the problems of deciding consistency for Disjunctive Linear Relations (DLRs). In this paper, we propose a new class of constraints called Extended DLRs consisting of disjunctions of linear inequalities, linear disequations and non-...

This paper presents the equivalence relationship between disjunctive and abductive logic programs. We show that the generalized stable model semantics of abductive logic programs can be translated into the possible model semantics of disjunctive programs, and vice versa. It is also proved that abductive disjunctive programs can be expressed by abductive logic programs under the possible model s...

We study the problem of rewriting a disjunctive datalog program into plain datalog. We show that a disjunctive program is rewritable if and only if it is equivalent to a linear disjunctive program, thus providing a novel characterisation of datalog rewritability. Motivated by this result, we propose weakly linear disjunctive datalog—a novel rule-based KR language that extends both datalog and l...

We propose a semantics for disjunctive logic programs, based on the single notion of forcing. We show that the semantics properly extends, in a natural way, previous approaches. A fixpoint characterization is also provided. We also take a closer look at the relationship between disjunctive logic programs and disjunctivefree logic programs. We present certain criteria under which a disjunctive p...

We present a framework of logic programming using an explicit representation of defeats of assumptions, called assumption denials. We study semantics for extended, disjunctive, and extended disjunctive programs, all in the same framework. The framework is based on a x-point operator over \uninterpreted programs", and semantics for various kinds of programs are then deened simply by adding appro...

Disjunctive systems are a representation of L-domains. They use sequents of the form X ` Y , with X nite and Y pairwise disjoint. We show that for any disjunctive system, its elements ordered by inclusion form an L-domain. On the other hand, via the notion of stable neighborhoods, every L-domain can be represented as a disjunctive system. More generally, we have a categorical equivalence betwee...