Constraints - An International Journal 

About: Constraints - An International Journal is an academic journal published by Springer Science+Business Media. The journal publishes majorly in the area(s): Constraint programming & Constraint satisfaction. It has an ISSN identifier of 1383-7133. Over the lifetime, 477 publications have been published receiving 13528 citations. The journal is also known as: Constraints (Boston).

Semiring-Based CSPs and Valued CSPs: Frameworks, Properties,and Comparison

Abstract: In this paper we describe and compare two frameworks for constraint solving where classical CSPs, fuzzy CSPs, weighted CSPs, partial constraint satisfaction, and others can be easily cast. One is based on a semiring, and the other one on a totally ordered commutative monoid. While comparing the two approaches, we show how to pass from one to the other one, and we discuss when this is possible. The two frameworks have been independently introduced in ijcai95,jacm and schiex-ijcai95.

Propagation via lazy clause generation

Abstract: Finite domain propagation solvers effectively represent the possible values of variables by a set of choices which can be naturally modelled as Boolean variables. In this paper we describe how to mimic a finite domain propagation engine, by mapping propagators into clauses in a SAT solver. This immediately results in strong nogoods for finite domain propagation. But a naive static translation is impractical except in limited cases. We show how to convert propagators to lazy clause generators for a SAT solver. The resulting system introduces flexibility in modelling since variables are modelled dually in the propagation engine and the SAT solver, and we explore various approaches to the dual modelling. We show that the resulting system solves many finite domain problems significantly faster than other techniques.

Constraint-Based Attribute and Interval Planning

Abstract: In this paper we describe Constraint-based Attribute and Interval Planning (CAIP), a paradigm for representing and reasoning about plans. The paradigm enables the description of planning domains with time, resources, concurrent activities, mutual exclusions among sets of activities, disjunctive preconditions and conditional effects. We provide a theoretical foundation for the paradigm, based on temporal intervals and attributes. We show how the plans are naturally expressed by networks of constraints, and show that the process of planning maps directly to dynamic constraint reasoning. We describe compatibilities, a compact mechanism for describing planning domains. We also demonstrate how this framework incorporates the use of constraint representation and reasoning technology to improve planning. Finally, we describe EUROPA, an implementation of the CAIP framework.

Practical applications of constraint programming

Abstract: Constraint programming offers facilities for problem modelling, constraint propagation and search. This paper discusses the resulting benefits for practical applications which exploit these facilities. The modelling facilities are particularly exploited in applications to verification, both of circuits and of real time control systems. The propagation facilities are exploited in applications involving user feedback and graphical interfaces. The search facilities are exploited in applications such as scheduling and resource allocation, which involve combinatorial problems. The paper surveys applications under each of these three headings.

Interval propagation to reason about sets: Definition and implementation of a practical language

Abstract: Local consistency techniques have been introduced in logic programming in order to extend the application domain of logic programming languages. The existing languages based on these techniques consider arithmetic constraints applied to variables ranging over finite integer domains. This makes difficult a natural and concise modelling as well as an efficient solving of a class of N P-complete combinatorial search problems dealing with sets. To overcome these problems, we propose a solution which consists in extending the notion of integer domains to that of set domains (sets of sets). We specify a set domain by an interval whose lower and upper bounds are known sets, ordered by set inclusion. We define the formal and practical framework of a new constraint logic programming language over set domains, called Conjunto. Conjunto comprises the usual set operation symbols(\ n), and the set inclusion relation (). Set expressions built using the operation symbols are interpreted as relations (s s 1 = s 2 ,...). In addition, Conjunto provides us with a set of constraints called graduated constraints (e.g. the set cardinality) which map sets onto arithmetic terms. This allows us to handle optimization problems by applying a cost function to the quantiiable, i.e., arithmetic, terms which are associated to set terms. The constraint solving in Conjunto is based on local consistency techniques using interval reasoning which are extended to handle set constraints. The main contribution of this paper concerns the formal deenition of the language and its design and implementation as a practical language.