Pountain, D.: Constraint Logic Programming, Byte, February, 1995.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Its highly declarative nature and its powerful solving methods have led to its commercial success. Many well known companies such as British Airways, Chrysler, Long Island Lighting Company, JD Edwards, and Whirlpool use constraint programming to manage various aspects of conducting business [Pountain,95] Wallace,96] ILOG OPT,98] 1.2 Problem Description Although powerful and robust, constraint programming is not a panacea. As problems grow larger in scale and complexity, they become harder and harder to solve. What s more, their execution times can exhibit inordinate growth. For some cases, ....

Pountain, D.: Constraint Logic Programming, Byte, February, 1995.

....Its highly declarative nature and its powerful solving methods have led to its commercial success. Several well known companies such as British Airways, Chrysler, Long Island Lighting Company, JD Edwards and Whirlpool use constraint programming to manage several aspects of conducting business [Pou95] ILO98] 1.1. Background. Constraint programming consists of two activities, problem description and problem solving. First, the problem is described in terms of its unknowns. This is usually accomplished by defining a set of decision variables and constraints. A decision variable is a pair ....

D. Pountain, Constraint logic programming, Byte (1995).

....number of variables used, resulting in a search space consisting of the permutation of variable set. The power of the constraint system is the elimination of the permutations that can not form a solution, hence the more non solution forming assignments are eliminated, the faster will be the search [4]. Like most CSPs [2] our project involves two phases. A preprocessing engine which would generate the constraint network of a given puzzle instance and a search engine to search all possible solutions using this network. The preprocessing phase parses the given puzzle and generates as much ....

D. Pountain, Constraint Logic Programming, BYTE (1995) 159160

....discarded without any further investigation. By focussing on a particular problem domain, and using the appropriate constraints, CLP implementations can execute with an efficiency comparable with imperative languages. Suitable introductions to CLP can be found in [FHK 92] Kri92] Las87] Pou95] and [Coh90] Difficult combinatorial problems which were previously intractable to logic programs could now be expressed cleanly in CLP and solved with the power of well known constraint techniques. Hence the uses of CLP are varied, and include building VLSI CAD tools [BBM94] industrial ....

D. Pountain. Constraint logic programming. BYTE Magazine, February 1995.

....are in general NP complete problems. However, by exploiting domain knowledge and manipulating constraints cleverly, researchers like [Fikes 1970] Montanari 1974] and [Mackworth 1977] have all shown that CSPs can be solved efficiently. CSPs can be solved using CLPs (Constraint Logic Programming) [Pountain 1995]. As the name suggests CLP is descended from logic programming, which shot to fame via the Prolog language as a consequence of the Japanese 5th Generation project and the expert systems boom of the mid 80 s. Now CLP languages make logic programs execute very efficiently by focussing on a ....

Dick Pountain, "Constraint Logic Programming", Byte magazine, February 1995.

....offering it as a fruitful, so we believe, logic pendant to Moggi s original idea. 2 Constraint Logic Programming CLP Constraint Logic Programming (CLP) is the result of a merger between two declarative paradigms constraint solving and logic programming ( FHK 92] Kri92] Las87] Pou95] are suitable introductions) In [JL87] Jaffar and Lassez propose a general scheme, CLP(X ) a logic programming framework which replaces unification with constraint solving in the domain of choice, X . In fact, unification can be seen as a special instance of constraint solving, specifically ....

D. Pountain. Constraint logic programming. BYTE Magazine, February 1995.

....by using a semi naive bottom up evalution technique. Hence we can be sure that the only solution is assign(9; 5; 6; 7; 1; 0; 8; 2) which was returned by DISCO. 2 Remark: A similar word puzzle was solved using linear rational constraints in the ECLIPSE constraint logic programming system [8]. 3.3 A Recursive Solution In many problems we have to order a set of items enumerated from 1 to n, such that the ordering satisfies a single relation constraint(y 1 ; y k ) that tells which k items can be acceptable subsequences. This is a more restrictive case of the general problem of ....

D. Pountain. Constraint Logic Programming. Byte, February 1995.

....to [CR94] which contains an introduction to constraint satisfaction in molecular biology and a more detailed explaination of some of the programs mentioned above. 4.3 Constraint Logic Programming 4.3. 1 Introduction to Constraint logic programming We base the following description on [JMSY92, Pou95] a general text is [Hen89] Constraint logic programming (CLP) is a based on constraint solving and the logic programming paradigm. In fact the CLP scheme describes a class of programming languages, of which Prolog is one member; in this sense, the CLP scheme is a generalisation of logic ....

Dick Pountain. Constraint Logic Programming. BYTE, Feb 1995.

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