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Logic program specialisation through partial deduction: Control issues
 THEORY AND PRACTICE OF LOGIC PROGRAMMING
, 2002
"... Program specialisation aims at improving the overall performance of programs by performing source to source transformations. A common approach within functional and logic programming, known respectively as partial evaluation and partial deduction, is to exploit partial knowledge about the input. It ..."
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Cited by 54 (12 self)
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Program specialisation aims at improving the overall performance of programs by performing source to source transformations. A common approach within functional and logic programming, known respectively as partial evaluation and partial deduction, is to exploit partial knowledge about the input. It is achieved through a wellautomated application of parts of the BurstallDarlington unfold/fold transformation framework. The main challenge in developing systems is to design automatic control that ensures correctness, efficiency, and termination. This survey and tutorial presents the main developments in controlling partial deduction over the past 10 years and analyses their respective merits and shortcomings. It ends with an assessment of current achievements and sketches some remaining research challenges.
Partial Deduction and Driving are Equivalent
, 1994
"... Partial deduction and driving are two methods used for program specialization in logic and functional languages, respectively. We argue that both techniques achieve essentially the same transformational effect by unificationbased information propagation. We show their equivalence by analyzing the ..."
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Cited by 46 (10 self)
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Partial deduction and driving are two methods used for program specialization in logic and functional languages, respectively. We argue that both techniques achieve essentially the same transformational effect by unificationbased information propagation. We show their equivalence by analyzing the definition and construction principles underlying partial deduction and driving, and by giving a translation from a functional language to a definite logic language preserving certain properties. We discuss residual program generation, termination issues, and related other techniques developed for program specialization in logic and functional languages.
Redundant Argument Filtering of Logic Programs
 Logic Program Synthesis and Transformation. Proceedings of LOPSTR’96, LNCS 1207
, 1996
"... This paper is concerned with the problem of removing, from a given logic program, redundant arguments. These are arguments which can be removed without affecting correctness. Most program specialisation techniques, even though they perform argument filtering and redundant clause removal, fail to re ..."
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Cited by 42 (17 self)
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This paper is concerned with the problem of removing, from a given logic program, redundant arguments. These are arguments which can be removed without affecting correctness. Most program specialisation techniques, even though they perform argument filtering and redundant clause removal, fail to remove a substantial number of redundant arguments, yielding in some cases rather inefficient residual programs. We formalise the notion of a redundant argument and show that one cannot decide effectively whether a given argument is redundant. We then give a safe, effective approximation of the notion of a redundant argument and describe several simple and efficient algorithms calculating based on the approximative notion. We conduct extensive experiments with our algorithms on mechanically generated programs illustrating the practical benefits of our approach.
Conjunctive Partial Deduction: Foundations, Control, Algorithms, and Experiments
 J. LOGIC PROGRAMMING
, 1999
"... ..."
Controlling Conjunctive Partial Deduction of Definite Logic Programs
, 1996
"... "Classical" partial deduction, within the framework by Lloyd and Shepherdson, computes partial deduction for separate atoms independently. As a consequence, a number of program optimisations, known from unfold/fold transformations and supercompilation, cannot be achieved. In this paper, we show that ..."
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Cited by 32 (9 self)
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"Classical" partial deduction, within the framework by Lloyd and Shepherdson, computes partial deduction for separate atoms independently. As a consequence, a number of program optimisations, known from unfold/fold transformations and supercompilation, cannot be achieved. In this paper, we show that this restriction can be lifted through (polygenetic) specialisation of entire atom conjunctions. We present a generic algorithm for such partial deduction and discuss its correctness in an extended formal framework. We concentrate on novel control challenges specific to this "conjunctive" partial deduction. We refine the generic algorithm into a fully automatic concrete one that registers partially deduced conjunctions in a global tree, and prove its termination and correctness. We discuss some further control refinements and illustrate the operation of the concrete algorithm and/or some of its possible variants on interesting transformation examples.
Conjunctive Partial Deduction in Practice
 Proceedings of the International Workshop on Logic Program Synthesis and Transformation (LOPSTR'96), LNCS 1207
, 1996
"... . Recently, partial deduction of logic programs has been extended to conceptually embed folding. To this end, partial deductions are no longer computed of single atoms, but rather of entire conjunctions; Hence the term "conjunctive partial deduction". Conjunctive partial deduction aims at achieving ..."
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Cited by 27 (19 self)
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. Recently, partial deduction of logic programs has been extended to conceptually embed folding. To this end, partial deductions are no longer computed of single atoms, but rather of entire conjunctions; Hence the term "conjunctive partial deduction". Conjunctive partial deduction aims at achieving unfold/foldlike program transformations such as tupling and deforestation within fully automated partial deduction. However, its merits greatly surpass that limited context: Also other major efficiency improvements are obtained through considerably improved sideways information propagation. In this extended abstract, we investigate conjunctive partial deduction in practice. We describe the concrete options used in the implementation(s), look at abstraction in a practical Prolog context, include and discuss an extensive set of benchmark results. From these, we can conclude that conjunctive partial deduction indeed pays off in practice, thoroughly beating its conventional precursor on a wide...
Ecological Partial Deduction: Preserving Characteristic Trees Without Constraints
 Logic Program Synthesis and Transformation. Proceedings of LOPSTR'95, LNCS 1048
, 1995
"... . A partial deduction strategy for logic programs usually uses an abstraction operation to guarantee the finiteness of the set of atoms for which partial deductions are produced. Finding an abstraction operation which guarantees finiteness and does not loose relevant information is a difficult probl ..."
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Cited by 24 (14 self)
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. A partial deduction strategy for logic programs usually uses an abstraction operation to guarantee the finiteness of the set of atoms for which partial deductions are produced. Finding an abstraction operation which guarantees finiteness and does not loose relevant information is a difficult problem. In earlier work Gallagher and Bruynooghe proposed to base the abstraction operation on characteristic paths and trees. A characteristic tree captures the relevant structure of the generated partial SLDNFtree for a given goal. Unfortunately the abstraction operations proposed in the earlier work do not always produce more general atoms and do not always preserve the characteristic trees. This problem has been solved for purely determinate unfolding rules and definite programs in [12, 13] by using constraints inside the partial deduction process. In this paper we propose an alternate solution which achieves the preservation of characteristic trees for any unfolding rule, normal logic prog...
Constrained Partial Deduction and the Preservation of Characteristic Trees
 NEW GENERATION COMPUTING
, 1997
"... Partial deduction strategies for logic programs often use an abstraction operator to guarantee the finiteness of the set of goals for which partial deductions are produced. Finding an abstraction operator which guarantees finiteness and does not lose relevant information is a difficult problem. I ..."
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Cited by 21 (16 self)
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Partial deduction strategies for logic programs often use an abstraction operator to guarantee the finiteness of the set of goals for which partial deductions are produced. Finding an abstraction operator which guarantees finiteness and does not lose relevant information is a difficult problem. In earlier work Gallagher and Bruynooghe proposed to base the abstraction operator on characteristic paths and trees, which capture the structure of the generated incomplete SLDNFtree for a given goal. In this paper we exhibit the advantages of characteristic trees over purely syntactical measures: if characteristic trees can be preserved upon generalisation, then we obtain an almost perfect abstraction operator, providing just enough polyvariance to avoid any loss of local specialisation. Unfortunately, the abstraction operators proposed in earlier work do not always preserve the characteristic trees upon generalisation. We show that this can lead to important specialisation losses as well as to nontermination of the partial deduction algorithm. Furthermore, this problem cannot be adequately solved in the ordinary partial deduction setting. We therefore extend the expressivity and precision of the Lloyd and Shepherdson partial deduction framework by integrating constraints. We provide formal correctness results for the so obtained generic framework of constrained partial deduction. Within this new framework we are, among others, able to overcome the above mentioned problems by introducing an alternative abstraction operator, based on so called pruning constraints. We thus present a terminating partial deduction strategy which, for purely determinate unfolding rules, induces no loss of local specialisation due to the abstraction while ensuring correctness o...
Unfold/Fold Transformations For Definite Clause Programs
 In Proceedings of PLILP, LNCS 844
, 1994
"... . An unfold/fold program transformation system which extends the unfold/fold transformations of H. Tamaki and T. Sato is presented in this paper. The system consists of unfolding, simultaneous folding, and generalization + equality introduction rules. The simultaneous folding rule permits the foldin ..."
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Cited by 17 (5 self)
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. An unfold/fold program transformation system which extends the unfold/fold transformations of H. Tamaki and T. Sato is presented in this paper. The system consists of unfolding, simultaneous folding, and generalization + equality introduction rules. The simultaneous folding rule permits the folding of a set of folded clauses into a single clause, using a set of folding clauses, while the generalization + equality introduction rule facilitates the application of the simultaneous folding rule by performing appropriate abstractions. A proof of the correctness of the proposed transformations in the sense of the least Herbrand model semantics of the program is also presented. 1 Introduction Unfold/fold transformations were first proposed by R. Burstall and J. Darlington [BD77] in the context of a functional language. In the context of logic programming, H. Tamaki and T. Sato [TS84, TS86] formulated unfold/fold transformations for definite clause programs so as to preserve the equivalence...
On Transformations into Linear Database Logic Programs
 Perspectives of Systems Informatics, 2nd International Andrei Ershov Memorial Conference, Akademgorodik
, 1996
"... Abstract. We consider the problem of transformations of logic programs without function symbols (database logic programs) into a special subclass, namely linear logic programs. Linear logic programs are dened to be the programs whose rules have at most one intentional atom in their bodies. a) We inv ..."
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Cited by 6 (5 self)
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Abstract. We consider the problem of transformations of logic programs without function symbols (database logic programs) into a special subclass, namely linear logic programs. Linear logic programs are dened to be the programs whose rules have at most one intentional atom in their bodies. a) We investigate linearizability of several syntactically de ned subclasses of programs and present both positive and negative results (i.e. demonstrate programs that cannot be transformed into a linear program by any transformation technique), and b) We develop an algorithm which transforms any program in a speci c subclass namely the piecewise logic programs into a linear logic program.