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- Kostas Stergiou, Manolis Koubarakis
- Artif. Intell.
- 1998

We extend the framework of simple temporal problems studied originally by Dechter, Meiri and Pearl to consider constraints of the form x1 ?y1 r1 and n 1. We have implemented four progressively more eecient algorithms for the consistency checking problem for this class of temporal constraints. We have partially ordered those algorithms according to the… (More)

- Kostas Stergiou, Toby Walsh
- AAAI/IAAI
- 1999

We perform a detailed theoretical and empirical comparison of the dual and hidden variable encodings of non-binary constraint satisfaction problems. We identify a simple relationship between the two encodings by showing how we can translate between the two by composing or decomposing relations. This translation suggests that we will tend to achieve more… (More)

- Kostas Stergiou, Nikos Samaras
- J. Artif. Intell. Res.
- 2005

A non-binary Constraint Satisfaction Problem (CSP) can be solved directly using extended versions of binary techniques. Alternatively, the non-binary problem can be translated into an equivalent binary one. In this case, it is generally accepted that the translated problem can be solved by applying well-established techniques for binary CSPs. In this paper… (More)

The Stochastic CSP (SCSP) is a framework recently introduced by Walsh to capture combinatorial decision problems that involve uncertainty and probabilities. The SCSP extends the classical CSP by including both decision variables, that an agent can set, and stochastic variables that follow a probability distribution and can model uncertain events beyond the… (More)

- Kostas Stergiou
- AI Commun.
- 2009

- Ian P. Gent, Peter Nightingale, Andrew Rowley, Kostas Stergiou
- Artif. Intell.
- 2008

We make a number of contributions to the study of the Quantified Constraint Satisfaction Problem (QCSP). The QCSP is an extension of the constraint satisfaction problem that can be used to model combinatorial problems containing contingency or uncertainty. It allows for universally quantified variables that can model uncertain actions and events, such as… (More)

- Konstantinos Kotis, George A. Vouros, Kostas Stergiou
- J. Web Sem.
- 2006

Latest research efforts on the semi-automatic coordination of ontologies " touch " on the mapping /merging of ontologies using the whole breadth of available knowledge. Addressing this issue, this paper presents the HCONE-merge approach, which is further extended towards automating the merging process. HCONE-merge makes use of the intended informal meaning… (More)

The Golomb ruler problem has been proposed as a challenging constraint satisfaction problem. We consider a large number of diierent models of this problem, both binary and non-binary. The problem can be modelled using quaternary constraints, but in practice using a set of auxiliary variables and ternary constraints gives better results. A binary encoding of… (More)

- Patrick Prosser, Kostas Stergiou, Toby Walsh
- CP
- 2000

We perform a comprehensive theoretical and empirical study of the benefits of singleton consistencies. Our theoretical results help place singleton consistencies within the hierarchy of local consistencies. To determine the practical value of these theoretical results, we measured the cost-effectiveness of pre-processing with singleton consistency… (More)

- Christian Bessiere, Kostas Stergiou, Toby Walsh
- Artif. Intell.
- 2008

In non-binary constraint satisfaction problems, the study of local consistencies that only prune values from domains has so far been largely limited to generalized arc consistency or weaker local consistency properties. This is in contrast with binary constraints where numerous such domain filtering consistencies have been proposed. In this paper we present… (More)