Programming languages are often classified according to their paradigms, e.g. imperative, functional, logic, constraint-based, object-oriented, or aspect-oriented. A paradigm characterizes the style, concepts, and methods of the language for describing situations and processes and for solving problems, and each paradigm serves best for programming in particular application areas. Real-world problems, however, are often best implemented by a combination of concepts from different paradigms, because they comprise aspects from several realms, and this combination is more comfortably realized using multiparadigm programming languages. This book deals with the theory and practice of multiparadigm constraint programming languages. The author first elaborates on programming paradigms and languages, constraints, and the merging of programming concepts which yields multiparadigm (constraint) programming languages. In the second part the author inspects two concrete approaches on multiparadigm constraint programming – the concurrent constraint functional language CCFL, which combines the functional and the constraint-based paradigms and allows the description of concurrent processes; and a general framework for multiparadigm constraint programming and its implementation, Meta-S. The book is appropriate for researchers and graduate students in the areas of programming and artificial intelligence.

This book constitutes the thoroughly refereed post-proceedings of the Joint ERCIM/Compulog-Net Workshop on New Trends in Constraints held in Paphos, Cyprus, Greece in October 1999. The 12 revised full research papers presented together with four surveys by leading researchers were carefully reviewed. The book is divided in topical sections on constraint propagation and manipulation, constraint programming, and rule-based constraint programming.

This volume contains selected and thoroughly revised papers plus contributions from invited speakers presented at the First International Workshop on C- straint Solving and Language Processing, held in Roskilde, Denmark, September 1–3, 2004. Constraint Programming and Constraint Solving, in particular Constraint Logic Programming, appear to be a very promising platform, perhaps the most promising present platform, for bringing forward the state of the art in natural language processing, this due to the naturalness in speci?cation and the direct relation to e?cient implementation. Language, in the present context, may - fer to written and spoken language, formal and semiformal language, and even general input data to multimodal and pervasive systems, which can be handled in very much the same ways using constraint programming. The notion of constraints, with slightly di?ering meanings, apply in the ch- acterization of linguistic and cognitive phenomena, in formalized linguistic m- els as well as in implementation-oriented frameworks. Programming techniques for constraint solving have been, and still are, in a period with rapid devel- ment of new e?cient methods and paradigms from which language processing can pro?t. A common metaphor for human language processing is one big c- straintsolvingprocessinwhichthedi?erent(-lyspeci?ed)linguisticandcognitive phases take place in parallel and with mutual cooperation, which ?ts quite well with current constraint programming paradigms.

Constraint programming is a powerful paradigm for solving combinatorial search problems that draws on a wide range of techniques from artificial intelligence, computer science, databases, programming languages, and operations research. Constraint programming is currently applied with success to many domains, such as scheduling, planning, vehicle routing, configuration, networks, and bioinformatics.The aim of this handbook is to capture the full breadth and depth of the constraint programming field and to be encyclopedic in its scope and coverage. While there are several excellent books on constraint programming, such books necessarily focus on the main notions and techniques and cannot cover also extensions, applications, and languages. The handbook gives a reasonably complete coverage of all these lines of work, based on constraint programming, so that a reader can have a rather precise idea of the whole field and its potential. Of course each line of work is dealt with in a survey-like style, where some details may be neglected in favor of coverage. However, the extensive bibliography of each chapter will help the interested readers to find suitable sources for the missing details. Each chapter of the handbook is intended to be a self-contained survey of a topic, and is written by one or more authors who are leading researchers in the area.The intended audience of the handbook is researchers, graduate students, higher-year undergraduates and practitioners who wish to learn about the state-of-the-art in constraint programming. No prior knowledge about the field is necessary to be able to read the chapters and gather useful knowledge. Researchers from other fields should find in this handbook an effective way to learn about constraint programming and to possibly use some of the constraint programming concepts and techniques in their work, thus providing a means for a fruitful cross-fertilization among different research areas.The handbook is organized in two parts. The first part covers the basic foundations of constraint programming, including the history, the notion of constraint propagation, basic search methods, global constraints, tractability and computational complexity, and important issues in modeling a problem as a constraint problem. The second part covers constraint languages and solver, several useful extensions to the basic framework (such as interval constraints, structured domains, and distributed CSPs), and successful application areas for constraint programming. - Covers the whole field of constraint programming- Survey-style chapters- Five chapters on applications

Constraint Programming is an approach for modeling and solving combi- torial problems that has proven successful in many applications. It builds on techniques developed in Arti?cial Intelligence, Logic Programming, and - erations Research. Key techniques are constraint propagation and heuristic search. Constraint Programming is based on an abstraction that decomposes a problem solver into a reusable constraint engine and a declarative program modeling the problem. The constraint engine implements the required pr- agation and search algorithms. It can be realized as a library for a general purpose programming language (e.g. C++), as an extension of an existing language (e.g. Prolog), or as a system with its own dedicated language. The present book is concerned with the architecture and implementation of constraint engines. It presents a new, concurrent architecture that is far superior to the sequential architecture underlying Prolog. The new archit- ture is based on concurrent search with copying and recomputation rather than sequential search with trailing and backtracking. One advantage of the concurrent approach is that it accommodates any search strategy. Furth- more, it considerably simpli?es the implementation of constraint propagation algorithms since it eliminates the need to account for trailing and backtra- ing. The book investigates an expressive generalization of the concurrent - chitecture that accommodates propagation-preserving combinators (known as deep guard combinators) for negation, disjunction, implication, and re- cation of constraint propagators. Such combinators are beyond the scope of Prolog’s technology. In the concurrent approach they can be obtained with a re?ective encapsulation primitive.

Multiparadigm languages are languages that are designed to support more than one style of programming. Leda is a strongly-typed multiparadigm programming language that supports imperative, functional, object-oriented, and logic programming. The constraint programming paradigm is a declarative style of programming where the programmer is able to state relationships among some entities and expect the system to maintain the validity of these relationships throughout program execution. The system accomplishes this either by invoking user-defined fixes that impose rigid rules governing the evolution of the entities, or by finding suitable values to be assigned to the constrained entities without violating any active constraint. Constraints, due to their declarative semantics, are suitable for the direct mapping of the characteristics of a number of mechanisms including: consistency checks, constraint-directed search, and constraint-enforced reevaluation, among others. This makes constraint languages the most appropriate languages for the implementation of a large number of applications such as scheduling, planning, resource allocation, simulation, and graphical user interfaces. The semantics of constraints cannot be easily emulated by other constructs in the paradigms that are offered by the language Leda. However, the constraint paradigm does not provide any general control constructs. The lack of general control constructs impedes this paradigm's ability to naturally express a large number of problems. This dissertation presents the language Electra, which integrates the constraint paradigm into the language Leda by creating a unified construct that provides the ability to express the conventional semantics of constraints with some extensions. Due to the flexibility of this construct, the programmer is given the choice of either stating how a constraint is to be satisfied or delegating that task to the constraint-satisfier. The concept of providing the programmer with the ability to express system-maintained relations, which is the basic characteristic of constraints, provided a motivation for enhancing other paradigms with similar abilities. The functional paradigm is extended by adding to it the mechanism of condition-based dispatching which is similar to argument pattern-matching. The object-oriented paradigm is extended by allowing feature exclusion which is a form of inheritance exception. This dissertation claims that the integration provided by the language Electra will enable Leda programmers to reap the benefits of the paradigm of constraints while overcoming its limitations.