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Refinements of Lazy Narrowing for LeftLinear FullyExtended Pattern Rewrite Systems Mircea Marin
, 2001
"... Lazy narrowing is a general Eunification procedure for equational theories presented by confluent term rewriting systems. It has been deeply studied in the first order case and various higherorder extensions have been proposed in an attempt to improve its expressive power. Such extensions suffer f ..."
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Lazy narrowing is a general Eunification procedure for equational theories presented by confluent term rewriting systems. It has been deeply studied in the first order case and various higherorder extensions have been proposed in an attempt to improve its expressive power. Such extensions suffer from huge search space in guessing the solutions of variables of functional type. For practical purposes, the need to reduce the search space of solutions is of paramount importance. In this paper we introduce HOLN, a higherorder lazy narrowing calculus for Eunification in theories presented by pattern rewrite systems. The calculus is designed to deal with both oriented and unoriented equations, and keeps track of the variables which are to be bound to normalized solutions. We discuss the operating principle of HOLN, its main properties, and propose refinements to reduce its search space for solutions. Our refinements are defined for classes of leftlinear fullyextended pattern rewrite systems which are widely used in higherorder functional logic programming.
Refinements of lazy narrowing for leftlinear fully extened pattern rewrite systems
, 2001
"... Abstract. Lazy narrowing is a general Eunification procedure for equational theories presented by confluent term rewriting systems. It has been deeply studied in the first order case and various higherorder extensions have been proposed in an attempt to improve its expressive power. Such extension ..."
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Abstract. Lazy narrowing is a general Eunification procedure for equational theories presented by confluent term rewriting systems. It has been deeply studied in the first order case and various higherorder extensions have been proposed in an attempt to improve its expressive power. Such extensions suffer from huge search space in guessing the solutions of variables of functional type. For practical purposes, the need to reduce the search space of solutions is of paramount importance. In this paper we introduce HOLN, a higherorder lazy narrowing calculus for Eunification in theories presented by pattern rewrite systems. The calculus is designed to deal with both oriented and unoriented equations, and keeps track of the variables which are to be bound to normalized solutions. We discuss the operating principle of HOLN, its main properties, and propose refinements to reduce its search space for solutions. Our refinements are defined for classes of leftlinear fullyextended pattern rewrite systems which are widely used in higherorder functional logic programming. 1
Higherorder Lazy Narrowing Calculi in Perspective
, 2000
"... Higherorder lazy narrowing (HOLN for short) is a computational model for higherorder functional logic programming. It can be viewed as an extension of firstorder lazy narrowing with inference rules to solve equations involving lambdaabstractions and higherorder variables. A common feature of th ..."
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Higherorder lazy narrowing (HOLN for short) is a computational model for higherorder functional logic programming. It can be viewed as an extension of firstorder lazy narrowing with inference rules to solve equations involving lambdaabstractions and higherorder variables. A common feature of the HOLN calculi proposed so far is the high nondeterminism between the inference rules designed to solve equations which involve higherorder variables. In this paper we present various refinements of HOLN towards more deterministic versions. The refinements are defined for classes of higherorder functional logic programs which are useful for programming purposes. Our work draws on two sources: the calculus LN for pattern rewrite systems [Pre98] and the firstorder lazy narrowing calculus LNC and its deterministic refinements [MO98].
Polymorphic Types in Functional Logic Programming ∗ J.C. GonzálezMoreno M.T. HortaláGonzález
"... ..."
An Open Environment for Cooperative Equational Solving
"... We describe a system called CFLP which aims at the integration of the best features of functional logic programming (FLP), cooperative constraint solving (CCS), and distributed computing. FLP provides support for defining one’s own abstractions over a constraint domain in an easy and comfortable way ..."
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We describe a system called CFLP which aims at the integration of the best features of functional logic programming (FLP), cooperative constraint solving (CCS), and distributed computing. FLP provides support for defining one’s own abstractions over a constraint domain in an easy and comfortable way, whereas CCS is employed to solve systems of mixed constraints by iterating specialized constraint solving methods in accordance with a well defined strategy. The system is a distributed implementation of a cooperative constraint functional logic programming scheme that combines higherorder lazy narrowing with cooperative constraint solving. The model takes advantage of the existence of several constraint solving resources located in a distributed environment (e.g., a network of computers), which communicate asynchronously via message passing. To increase the openness of the system, we are redesigning CFLP based on CORBA. We discuss some design and implementation issues of the system. 1.
A Deterministic Lazy Conditional Narrowing Calculus
, 2002
"... We show the completeness of a deterministic lazy conditional narrowing calculus with leftmost selection for the class of eftlinear fresh deterministic constructorbased conditional rewrite systems. This class of rewrite systems permits extra variables in the righthand sides and conditions of its r ..."
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We show the completeness of a deterministic lazy conditional narrowing calculus with leftmost selection for the class of eftlinear fresh deterministic constructorbased conditional rewrite systems. This class of rewrite systems permits extra variables in the righthand sides and conditions of its rewrite rules. This result is relevant for the designers of suitable computational models for functional logic programming, where the reduction of search space for solutions of systems of equations in theories presented by conditional rewrite systems is of paramount importance.
An Open Environment for Cooperative Equational Solving
, 2001
"... We describe a system called CFLP which aims at the integration of the best features of functional logic programming (FLP), cooperative constraint solving (CCS), and distributed computing. FLP provides support for defining one's own abstractions over a constraint domain in an easy and comfortabl ..."
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We describe a system called CFLP which aims at the integration of the best features of functional logic programming (FLP), cooperative constraint solving (CCS), and distributed computing. FLP provides support for defining one's own abstractions over a constraint domain in an easy and comfortable way, whereas CCS is employed to solve systems of mixed constraints by iterating specialized constraint solving methods in accordance with a well defined strategy. The system is a distributed implementation of a cooperative constraint functional logic programming scheme that combines higherorder lazy narrowing with cooperative constraint solving. The model takes advantage of the existence of several constraint solving resources located in a distributed environment (e.g., a network of computers), which communicate asynchronously via message passing. To increase the openness of the system, we are redesigning CFLP based on CORBA. We discuss some design and implementation issues of the system.
An Open Environment for Cooperative Equational Solving
"... We describe a system called CFLP which aims at the integration of the best features of functional logic programming (FLP), cooperative constraint solving (CCS), and distributed computing. FLP provides support for defining one’s own abstractions over a constraint domain in an easy and comfortable way ..."
Abstract
 Add to MetaCart
(Show Context)
We describe a system called CFLP which aims at the integration of the best features of functional logic programming (FLP), cooperative constraint solving (CCS), and distributed computing. FLP provides support for defining one’s own abstractions over a constraint domain in an easy and comfortable way, whereas CCS is employed to solve systems of mixed constraints by iterating specialized constraint solving methods in accordance with a well defined strategy. The system is a distributed implementation of a cooperative constraint functional logic programming scheme that combines higherorder lazy narrowing with cooperative constraint solving. The model takes advantage of the existence of several constraint solving resources located in a distributed environment (e.g., a network of computers), which communicate asynchronously via message passing. To increase the openness of the system, we are redesigning CFLP based on CORBA. We discuss some design and implementation issues of the system. 1.