A. Bossi and S. Etalle. Transforming acyclic programs. ACM Transactions on Programming Languages and Systems, 16(4):1081-1096, 1994.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....for m 0, n 0 If ack is partially evaluated wrt. its first argument being 2, the following level 1 rules (specialized versions of ack) will typically be generated: The concept of PE may be extended a bit, as e.g. in [Tak91] where context is taken into account, and in [BCD90] where a function can be specialized wrt. an argument satisfying some predicate. 25 If we introduce ack2, ack1 and ack0 such that ack2(n) is an abbreviation (cf. the discussion in section 2.1.2) of ack(2,n) etc, the level 1 rules will take the form and will thus constitute a ....

A. Bossi, N. Cocco, and S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253--302, April 1990.

....and for automatic specializations based on the parameterized strategy presented in Section 2.5. The MAP system is described in Appendix A. The source code for the examples can be found in Appendix B. There are various methods for specializing programs w.r.t. properties of their input data [10, 16, 53, 61, 66]. Contextual specialization can be viewed as one of these methods. In this chapter we have presented a set of transformation rules and an automated strategy for the contextual specialization of constraint logic programs over a domain For our specialization strategy we have assumed the existence ....

....the clause generalization process during program specialization. We have shown that our specialization strategy pre serves the least ) model and it terminates. 2.1U. IELA ID The hypothesis that the function solve is complete w.r.t. satisfiability, makes our approach different from the one in [10], where program special ization is based on some undecidable properties and thus, it cannot be easily automated. Partial evaluation of logic programs [50] also called partial deduction, is the technique for program specialization which is most related to ours. However, we would like to mention ....

BossI, A., Cocco, N., AND DULLI, S. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems 12, 2 (April 1990), 253-302.

....Since state changes are usually not drastic for popular games, the true dynamic facts in two di erent states tend to only slightly vary. In such cases, the incremental maintenance technique of such materialized views can be useful. In our approach, we use the partial evaluation technique[2] for speeding up the evaluation of such rules. By repeatedly applying unfolding and pruning, we can make each rule fully expanded until the body of the rule consists of dynamic facts only. Theoretically, the unfolding and pruning process may continue Compiling Logical Features into Specialized ....

....of the partial evaluation, Boolean tables, and incremental calculation. 3. 1 Partial Evaluation First, given features are transformed into the equivalent set of ground clauses (i.e. clauses without variables) Two operations, unfolding and pruning in partial evaluation of logic programming[2] are used. Unfolding Unfolding is an operation to replace a clause A : A 1 ; A i ; An with clauses (A : A 1 ; A i 1 ; B 1 ; B h ; A i 1 ; An ) j for B : B 1 ; B h such that B j = A i j for some substitution j . In this paper, we apply the unfolding from the ....

A. Bossi, N. Cocco, and S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253-302, 1990.

....counters to guide folding. Maher described a system that permits only reversible folding [Mah87] The basic Tamaki Sato system itself was extended in several directions (e.g. to handle folding with multiple clauses [GK94] negation [AD95, Sek91, Sek93] and applied to practical problems (e.g. BCD90, BB93, PPR97] All the above systems di er from each other mainly in terms of the fold operations they permit. Research done while on leave from Chennai Mathematical Institute, Chennai, India. 1 Correctness of Unfold Fold Transformations Consider the sequence of programs in Figure 1. In ....

A. Bossi, N. Cocco, and S. Dulli. A method of specializing logic programs. ACM Transactions on Programming Languages and Systems, pages 253-302, 1990.

....that can be applied to our deduction system in order to completely automate the deductive process. 1. 1 Related Work Related Work : Program Transformations Unfold fold logic program transformation systems have been extensively used for program synthesis, specialization and optimization [BCD90, BB93, LSW96, PPR97, PP99a] 4 However, relatively little work has been done on using such systems for constructing proofs. Hsiang and Srivas [HS87] extended Prolog s evaluation with limited forward chaining to perform inductive theorem proving. This limited forward chaining step is in fact a ....

....counters to guide folding. Maher described a system that permits only reversible folding [Mah87] The basic Tamaki Sato system itself was extended in several directions (e.g. to handle folding with multiple clauses [GK94] negation [AD95, Sek91, Sek93] and applied to practical problems (e.g. BCD90, BB93, PPR97] See [PP98] for an excellent survey of research on this topic over the past decade) 8 Correctness of Unfold Fold Transformations Correctness proofs for unfold fold transformations consider transformation sequences of the form P 0 ; P 1 ; where P 0 is an initial program ....

A. Bossi, N. Cocco, and S. Dulli. A method of specializing logic programs. ACM Transactions on Programming Languages and Systems, pages 253-302, 1990.

.... programs [11, 20] based on extensions Contextual Specialization of Constraint Logic Programs of Lloyd and Shepherdson s approach [13] also called partial deduction in the literature) and we also compare our method to other specialization techniques based on the unfold fold transformation rules [2, 7]. 2 Preliminaries The Constraint Logic Programming scheme [8] is an extension of the standard logic programming paradigm which allows the integration of constraints with a prede ned interpretation. It de nes a class of languages which are parametric in the choice of the constraint domain D, that ....

....a possibly in nite set of values, instead of a single value. Indeed, our specialization method belongs to the family of methods for the specialization of program w.r.t. properties of the context. Among these, we would like to mention: 1) the methods for specializing logic programs presented in [2] and [16] and (2) the method for parametrized partial evaluation of functional programs presented in [4] The works [2] and [16] present very general approaches which, however, do not seem to be amenable to full mechanization. In particular, in [2] most of the basic transformation rules cannot be ....

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A. Bossi, N. Cocco, and S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253-302, April 1990.

....the method of [12, 21] nor the method of [11] preserve the finite failure semantics (i.e. infinite failure might be replaced by finite failure) while our approach, just like ordinary partial deduction, does. Another method that might look like a viable alternative to our approach is the one of [5], situated within the context of unfold fold transformations. In particular, 5] contains many transformation rules and allows first order logic formulas to be used to constrain the specialisation. It is thus a very powerful framework. But also, because of that power, controlling it in an ....

....(i.e. infinite failure might be replaced by finite failure) while our approach, just like ordinary partial deduction, does. Another method that might look like a viable alternative to our approach is the one of [5] situated within the context of unfold fold transformations. In particular, [5] contains many transformation rules and allows first order logic formulas to be used to constrain the specialisation. It is thus a very powerful framework. But also, because of that power, controlling it in an automatic way, as well as ensuring actual efficiency gains, is much more difficult. A ....

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A. Bossi, N. Cocco, and S. Dulli. A method for specialising logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253--302, 1990.

....on maintaining counters to guide folding. Maher described a system that permits only reversible folding [8] The basic Tamaki Sato system itself was extended in several directions (e.g. to handle folding with multiple clauses [5] negation [1, 12, 13] and applied to practical problems (e.g. [2, 3, 10]) See [9] for an excellent survey of research on this topic over the past decade) Correctness of Unfold Fold Transformations Correctness proofs for unfold fold transformations consider transformation sequences of the form P 0 ; P 1 ; where P 0 is an initial program and P i 1 is ....

A. Bossi, N. Cocco, and S. Dulli. A method of specializing logic programs. ACM Transactions on Programming Languages and Systems, pages 253--302, 1990.

....for definite programs. An unfold fold transformation system for definite logic programs was first described in a seminal paper by Tamaki and Sato [23] Since then their system has been substantially extended and expanded [1, 8, 12, 22, 24] and applied to practical problems of importance (e.g. see [2, 4, 14, 17]) An excellent survey of research on this topic appears in [16] Unfold fold logic program transformation systems have been extensively used for program synthesis and program optimization. However, relatively little work has been done on using such systems for constructing proofs. Hsiang and ....

A. Bossi, N. Cocco, and S. Dulli. A method of specializing logic programs. ACM Transactions on Programming Languages and Systems, pages 253--302, 1990.

.... specialization and differencelist transformation examples we have presented cannot be derived in a natural way by using the unfold fold transformations of [28] Some modified versions of the rules should be used instead, like, for instance, the unfold fold rules with constraints introduced by [3] for specializing logic programs, or the inverse definition and the data structure mapping introduced by [31] Our last example on the avoidance of nondeterminism shows that the unfold fold transformation technique enhanced with our synthesis method, is able to derive programs for which other ....

A. Bossi, N. Cocco, and S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253--302, April 1990.

....term. Some extensions of partial evaluation, both of functional and logic programs, have been proposed to deal with static properties of input data, instead of static values. These extensions incorporate complex forms of reasoning based on abstract interpretation [3, 4] and theorem proving [1, 5]. By contrast, we propose a new technique which is based on the unfolding rule and a very limited form of goal replacement. On the one hand, this technique allows us to specify static properties in a precise way (unlike abstract interpretation) and, on the other hand, we avoid the use of very ....

....of clauses in P on which the evaluation of q(X) may depend. We observe that Condition (2) is equivalent to the following condition: for every ground substitution for X; M(P ) j= fq(X)g p(X) iff M(Q [ P 1 ) j= fq(X)g p 1 (X) 3) where fSg D is an alternative notation (borrowed from [1]) for the conjunction (S; D) which explicitly indicates that S is a property that holds when the evaluation of D is performed. If Condition (3) holds we say that hP 1 ; p 1 (X)i is a specialization of P w.r.t. the static part of the goal fq(X)g p(X) Condition (3) is equivalent to M(P [ P 1 ....

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A. Bossi, N. Cocco, and S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253--302, April 1990.

....that program is used. This knowledge can be expressed as a precondition which is satisfied by the values of the input to the program. No much work has been done in the area of logic program specialization, apart from the particular case of partial deduction. However, some results are reported in [ Bossi et al. 1990 ] and in various papers by Gallagher and others [ Gallagher et al. 1988; Gallagher and Bruynooghe, 1991; de Waal and Gallagher, 1992 ] In the latter papers the use of the abstract interpretation methodology plays a crucial role. Using this methodology one can represent and manipulate a possibly ....

....Lloyd, 1990; Bruynooghe et al. 1992; Gallagher, 1991; Martens et al. 1992; Gallagher, 1993 ] Some of them require generalization steps and the use of abstract interpretations. Other techniques for partial evaluation and program specialization are based on the unfold fold rules [ Fujita, 1987; Bossi et al. 1990; Sahlin, 1993; Bossi and Cocco, 1993; Prestwich, 1993a; Proietti and Pettorossi, 1993 ] By using those techniques, given a program P and a query G, we introduce a new predicate newp defined by the clause D. newp(X 1 ; Xn ) G where X 1 ; Xn are the variables occurring in ....

A. Bossi, N. Cocco, and S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253--302, April 1990.

.... and Maurizio Proietti [ Kott, 1978; Kanamori and Fujita, 1986; Bossi et al. 1992a ] An alternative approach is based on the verification that some termination properties are preserved by the transformation process, thereby avoiding the introduction of infinite computations [ Amtoft, 1992; Bossi and Etalle, 1994b; Bossi and Cocco, 1994; Cook and Gallagher, 1994 ] The following definition introduces the version of the folding rule we have promised above. This version is a special case of rule R2 for n = 1. Rule R2.2 Single Folding. Let C be a clause in program P k and D be a clause in a program P j , ....

.... [ Kott, 1978; Kanamori and Fujita, 1986; Bossi et al. 1992a ] An alternative approach is based on the verification that some termination properties are preserved by the transformation process, thereby avoiding the introduction of infinite computations [ Amtoft, 1992; Bossi and Etalle, 1994b; Bossi and Cocco, 1994; Cook and Gallagher, 1994 ] The following definition introduces the version of the folding rule we have promised above. This version is a special case of rule R2 for n = 1. Rule R2.2 Single Folding. Let C be a clause in program P k and D be a clause in a program P j , for some j, with 0 j k. ....

[Article contains additional citation context not shown here]

A. Bossi and S. Etalle. Transforming acyclic programs. ACM Transactions on Programming Languages and Systems, 16(4):1081--1096, July 1994.

....and tupling [6] are two automatic instances of the technique. Similar transformations have been introduced in logic programming [31, 27] for removing redundant variables from logic programs [28] The relationship between partial deduction and unfold fold transformation has already been discussed [3, 29, 27] but with an emphasis on how specialisation of logic programs can be understood in an unfold fold setting. Pettorossi and Proietti [27] describe a technique for classical partial deduction based on unfold fold rules. Their technique relies on a simple folding strategy involving no generalisation, ....

A. Bossi, N. Cocco, S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253--302, 1990.

....specialization of logic A preliminary version of this paper appears as: Reducing Nondeterminism while Specializing Logic Programs. Proceedings of the 24th Annual ACM Symposium on Principles of Programming Languages, Paris, France, January 15 17, 1997, ACM Press, 1997, pp. 414 427. 1 programs [4, 35, 36, 40]. In particular, we consider de nite logic programs [27] and we propose new program specialization techniques based on unfold fold transformation rules [6, 45] In our approach, the process of program specialization can be viewed as the construction of a sequence, say P 0 ; P n , of ....

A. Bossi, N. Cocco, and S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253-302, April 1990.

....instead of a single value. Indeed, our specialization method belongs to a family of methods which can be used for the specialization of programs w.r.t. properties of their context of use. Among these methods we would like to mention: i) the methods for specializing logic programs presented in [2,15], ii) the method for multiple specialization of logic programs presented in [19] iii) the method for reducing the workload of the constraint solving engine presented in [14] and (iv) the method for parameterized partial evaluation of functional programs presented in [3] In [2,15] the authors ....

.... presented in [2,15] ii) the method for multiple specialization of logic programs presented in [19] iii) the method for reducing the workload of the constraint solving engine presented in [14] and (iv) the method for parameterized partial evaluation of functional programs presented in [3] In [2,15] the authors present very general approaches to the specialization of definite logic programs w.r.t. properties which, however, do not seem to be amenable to full mechanization. In particular, most of the basic trans11 Fioravanti, Pettorossi, and Proietti formation rules introduced in [2] cannot ....

[Article contains additional citation context not shown here]

A. Bossi, N. Cocco, and S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253--302, April 1990.

....whose goal is the automatic adaptation of a program to the context in which it is used. There are two main approaches for achieving program specialization of constraint logic programs: the standard approach based on partial evaluation [10, 11, 16] and the approach based on unfold fold rules [2, 4]. In CLP, the context of use is naturally expressed by constraints, which may denote possibly in nite sets of values. In [5, 6] we have investigated the specialization of constraint logic programs w.r.t. properties. In particular, we have introduced novel transformation rules tailored to program ....

A. Bossi, N. Cocco, and S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253 302, April 1990.

....(i.e. J becomes instantiated) In the above example this happened to not(trigger(X) This implies that after the unfold operation some calls might be more instantiated than before the unfold. On the other hand, for general programs we can say that the unfold operation maintains acyclicity [BE94] and acceptability [BCE96b] If P is acyclic (resp. acceptable wrt a certain level mapping j j and a model M) and P 0 is obtained from P by the application of an unfold operation, then P 0 is acyclic as well (resp. acceptable wrt j j and M as well) Another consequence of the already ....

....to make syntactically checkable this condition. 12 Termination Properties We discuss now what happens when we are interested in preserving more procedural properties such as termination ones. If we consider termination wrt all selection rules, then the system we present here is correct: In [BE94] we proved that if the initial program is (definite and) terminating for all selection rules, then the transformed program is terminating for all selection rules as well. This result extends also to general programs by considering the concept of acyclic program: If the initial program is acyclic ....

A. Bossi and S. Etalle. Transforming Acyclic Programs. ACM Transactions on Programming Languages and Systems, 16(4):1081--1096, July 1994.

....instead of a single value. Indeed, our specialization method belongs to a family of methods which can be used for the specialization of programs w.r.t. properties of their context of use. Among these methods we would like to mention: i) the methods for specializing logic programs presented in [2, 14], ii) the method for multiple specialization of logic programs based on abstract interpretation presented in [18] and (iii) the method for parameterized partial evaluation of functional programs presented in [3] In [2, 14] the authors present very general approaches to the specialization of ....

.... to mention: i) the methods for specializing logic programs presented in [2, 14] ii) the method for multiple specialization of logic programs based on abstract interpretation presented in [18] and (iii) the method for parameterized partial evaluation of functional programs presented in [3] In [2, 14] the authors present very general approaches to the specialization of logic programs w.r.t. properties which, however, do not seem to be amenable to full mechanization. In particular, most of the basic transformation rules introduced in [2] cannot be easily automated because their applicability ....

[Article contains additional citation context not shown here]

A. Bossi, N. Cocco, and S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253302, April 1990.

.... specialization and di erence list transformation examples we have presented cannot be derived in a natural way by using the unfold fold transformations of [28] Some modi ed versions of the rules should be used instead, like, for instance, the unfold fold rules with constraints introduced by [3] for specializing logic programs, or the inverse de nition and the data structure mapping introduced by [31] Our last example on the avoidance of nondeterminism shows that the unfold fold transformation technique enhanced with our synthesis method, is able to derive programs for which other ....

A. Bossi, N. Cocco, and S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253-302, April 1990. 227

....is slightly more restrictive than the one of [TS84] Our system is based on a modularization of the program which distinguishes the part which can be transformed and guides the transformation. Other approaches to preserving termination properties, while transforming a program, can be found in [PP91,CG94,BE94,BC94,BC97]. The work of Proietti and Pettorossi in [PP91] made an important step forward in the direction of the preservation of left termination. They proposed a transformation system which is more restrictive than the ordered version of [TS84] since only unfolding the leftmost atom or a deterministic ....

....a system preserves the sequence of answer substitution semantics (a semantics for Prolog programs, defined in [JM84,Bau89] This guarantees also that if the initial program is left terminating, then the resulting program is left terminating as well. They do not allow any reordering of atoms. In [BE94] we proved that Tamaki Sato s transformation system preserves the property of being acyclic [AB90] This has to do with the preservation of termination, in fact a definite program P is acyclic if and only if all its derivations starting in a ground goal are finite whichever is the selection rule ....

[Article contains additional citation context not shown here]

A. Bossi and S. Etalle. Transforming Acyclic Programs. ACM Transactions on Programming Languages and Systems, 16(4):1081--1096, July 1994.

....and Cocco [4] focus their study on definite logic programs which are evaluated using the PROLOG leftmost computation rule. They prove that restricted versions of Tamaki and Sato s unfolding and folding preserve both the set of computed answer substitutions and PROLOG semantics. Bossi and Etalle [5] consider general logic programs and show that Tamaki and Sato s rules preserve acyclicity of programs. Recently, advances in the study of logic programs termination have stimulated the investigations of the relationship between program transformation and program termination. The paper by Lau, ....

A. Bossi, S. Etalle. Transforming acyclic programs. ACM Transactions on Programming Languages and Systems, 16(4):1081-796, July 1994.

....a more efficient program which behaves as the original one on the considered subdomain. In the field of logic programming, the narrowed context is usually described by means of a set of queries of interest. Specialisation methods are based on the idea of partially evaluating program clauses [5, 16, 20, 21] with respect to this set of queries. The goal is to detect clauses which are redundant in the restricted context, or to specialise them preventing costly failing derivations. If the original program is correct with respect to a pre post specification [4, 9, 10, 2] and the considered queries ....

A. Bossi, N. Cocco, and S. Dulli. A Method for Specializing Logic Programs. ACM Transactions on Programming Languages and Systems, 12(2):253--302, 1990.

No context found.

A. Bossi and S. Etalle. Transforming acyclic programs. ACM Transactions on Programming Languages and Systems, 16(4):1081-1096, 1994.

No context found.

A. Bossi, N. Cocco, and S. Dulli. A method for specializing logic programs. ACM Transactions on Programming Languages and Systems, 12(2):253-- 302, 1990.

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