M. Alpuente, M. Falaschi, G. Moreno, and G. Vidal. Safe Folding/Unfolding with Conditional Narrowing. In Proc. ALP'97, pages 1--15. Springer LNCS 1298, 1997.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....of a program using the definitions of this program (or of a preceding one) Other rules which have been considered are, for example: instantiation, definition introduction elimination, and abstraction. The first attempt to introduce these ideas in an integrated language is presented in [2], where we investigated fold unfold rules in the context of a strict (call by value) functional logic language. A transformation methodology for lazy (call by name) functional logic programs was introduced in [3] this work extends the transformation rules of [22] for logic programs in order to ....

M. Alpuente, M. Falaschi, G. Moreno, and G. Vidal. Safe folding/unfolding with conditional narrowing. In H. Heering M. Hanus and K. Meinke, editors, Proc. of the International Conference on Algebraic and Logic Programming, ALP'97, Southampton (England), pages 1--15. Springer LNCS 1298, 1997.

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M. Alpuente, M. Falaschi, G. Moreno, and G. Vidal. Safe Folding/Unfolding with Conditional Narrowing. In Proc. ALP'97, pages 1--15. Springer LNCS 1298, 1997.

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M. Alpuente, M. Falaschi, G. Moreno, and G. Vidal. Safe Folding/Unfolding with Conditional Narrowing. Technical Report DSIC-II/3/97, DSIC, UPV, 1997.

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M. Alpuente, M. Falaschi, G. Moreno, and G. Vidal. Safe folding/unfolding with conditional narrowing. In H. Heering M. Hanus and K. Meinke, editors, Proc. of the International Conference on Algebraic and Logic Programming, ALP'97, Southampton (England), pages 1--15. Springer LNCS 1298, 1997. 45

....Remove from all those rules that do not occur in refutations of equations in E k 1 = r # X Let k : k 1 end While Return Fig. 2. Basic algorithm for program correction folding w.r.t. computed answers in functional logic languages with eager lazy semantics can be found in [6,7]. Following [19] we use the unfolding operator for program correction as follows. We formulate a basic algorithm which specializes programs w.r.t. positive and negative examples by applying the transformation rule unfolding together with rule removal. The (backbone of the) algorithm, to be used ....

....problem was proposed which applies the transformation rules unfolding, definition, and folding. In the context of functional logic languages, a formal definition of these rules as well as proofs of their meaning preserving property (when they are combined) w.r.t. computed answers can be found in [6,7]. We plan to pursue an example guided fold unfold methodology for program correction as further research. 8 Implementation The basic methodology presented so far has been implemented by a prototype system Buggy [2,4] which is written in SICStus Prolog and available at ....

M. Alpuente, M. Falaschi, G. Moreno, and G. Vidal. Safe folding/unfolding with conditional narrowing. In H. Heering M. Hanus and K. Meinke, editors, Proc. of the International Conference on Algebraic and Logic Programming, ALP'97, Southampton (England), pages 1--15. Springer LNCS 1298, 1997.

.... i ( C i )ji = 1 : ng (that is, the derived goal (C i = y) is di erent from g. De nition 4 (Unfolding operator) Let R be a CTRS, r ( C be a rule in R. The Rule Unfolding operator U r (R) on R w.r.t. r is de ned by U r (R) R n frg [ R (r) As it has been proven in [5, 6], for = inn; needed, unfolding using strategy preserves the semantics (even for the observable of computed answers) in IR programs. In the case when needed narrowing is considered, completeness is only guaranteed under the condition that expressions in the rule are not unfolded beyond their ....

M. Alpuente, M. Falaschi, G. Moreno, and G. Vidal. Safe folding/unfolding with conditional narrowing. In H. Heering M. Hanus and K. Meinke, editors, Proc. of the International Conference on Algebraic and Logic Programming, ALP'97, Southampton (England), pages 1-15. Springer LNCS 1298, 1997.

....r; Remove from X all those rules that do not occur in refutations of equations in E Let k l : k r U X Let k : k 1 end While Return T Fig. 2. Basic algorithm for program correction folding w.r.t. computed answers in functional logic languages with eager lazy semantics can be found in [5,6]. Following [18] we use the unfolding operator for program correction as follows. We formulate a basic algorithm which specializes programs w.r.t. positive and negative examples by applying the transformation rule unfolding together with rule removal. The (backbone of the) algorithm, to be used ....

....problem was proposed which applies the transformation rules unfolding, definition, and folding. In the context of functional logic languages, a formal definition of these rules as well as proofs of their meaning preserving property (when they are combined) w.r.t. computed answers can be found in [5,6]. We plan to pursue an example guided fold unfold methodology for program correction as further research. 8 Implementation The basic methodology presented so far has been implemented by a prototype system BuccY [2,3] which is written in SICStus Prolog and available at http: www. dsic.upv. ....

M. Alpuente, M. Falaschi, G. Moreno, and G. Vidal. Safe folding/unfolding with conditional narrowing. In H. Heering M. Hanus and K. Meinke, editors, Proc. of the International Conference on Algebraic and Logic Programming, ALP'97, Southampton (England), pages 1-15. Springer LNCS 1298, 1997.

....in functional programming, the most general and recent work is [34] which defines a simple (syntactic) condition for restricting general fold unfold transformations and which can be applied to give correctness proofs for several well known transformation methods, such as the deforestation. In [2], we investigated fold and unfold rules in the context of a strict (call by value) functional logic language with an operational principle based on unrestricted (i.e. not optimized) narrowing. The use of narrowing empowers the fold unfold system by implicitly embedding the instantiation rule (the ....

....(i.e. not optimized) narrowing. The use of narrowing empowers the fold unfold system by implicitly embedding the instantiation rule (the operation of the Burstall and Darlington framework [8] which introduces an instance of an existing equation) into unfolding by means of unification. However, [2] does not consider a general transformation system (only two rules: fold and unfold) hence the composition or tupling transformations cannot be achieved. Also, 2] refers to a notion of reversible folding, which is strictly weaker than the one which we consider here. On the other hand, the use ....

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M. Alpuente, M. Falaschi, G. Moreno, and G. Vidal. Safe folding/unfolding with conditional narrowing. In H. Heering M. Hanus and K. Meinke, editors, Proc. of the International Conference on Algebraic and Logic Programming, ALP'97, Southampton (England), pages 1--15. Springer LNCS 1298, 1997.

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M. Alpuente, M. Falaschi, G. Moreno, and G. Vidal. Safe folding/unfolding with conditional narrowing. In H. Heering M. Hanus and K. Meinke, editors, Proc. of the International Conference on Algebraic and Logic Programming, ALP'97, Southampton (England), pages 1--15. Springer LNCS 1298, 1997.

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