Nadathur, G. and Jayaraman, B. Towards a WAM model for #Prolog. To appear in the Proceedings of the North American Conference on Logic Programming, MIT Press, 1989.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....map has the type (A B) listA) listB) o (where A; B are type variables and o is the type of propositions) Cube adopted these two features from Prolog. A prototype interpreter for Prolog has been implemented, and a more efficient, abstractmachine based implementation is under way [54]. HiLog [12] is a logic programming language with a higher order syntax, but a first order semantics. There is no distinction between terms and atomic formulas. Two terms denoting predicates are considered to be equal if their intensions are equal (e.g. if they are denoted by the same symbol) no ....

Gopalan Nadathur and Bharat Jayaraman. Towards a WAM Model for Prolog. In Ewing L. Lusk and Ross A. Overbeck, editors, Logic Programming: Proceedings of the North American Conference 1989, pages 1180 -- 1198, MIT Press, Cambridge, MA, 1989.

....run times in seconds, log log scale) It has not been possible to compare our system with the other most recent attempts for implementing Prolog (Nadathur, Jayaraman, Felty) because of the lack of availability of complete systems. However, papers and technical reports by Nadathur and Jayaraman [33, 20, 19] show that their approach and ours are somewhat different and difficult to compare on the paper. In few words, they choose to base their design on a WAM augmented for handling Prolog s specifics. P. Brisset and O. Ridoux 19 20 40 60 80 100 120 140 160 180 200 0 1000 2000 3000 4000 5000 ....

G. Nadathur and B. Jayaraman. Towards a WAM model for Prolog. In E.L. Lusk and R.A. Overbeek, editors, 1st North American Conf. Logic Programming, pages 1180--1198, MIT Press, Cleveland, OH, 1989.

.... f(e 1 ; e n ) is activated ( force list) when X is bound to non variable term literals of force list proved after unification of clause head 3 different dereferencing mechanisms force meta predicate ffl A WAM [Ha91] ALF, normalizing innermost basic narrowing) ffl WAM [NJ89] extension for Prolog, including higher order unification 38 2) Extension of reduction machine by choice points trail ffl IBAM [KLMR90] innermost Babel, innermost narrowing) graph based ffl LBAM [MKLR90] Babel, lazy narrowing) graph based ffl JUMP [CL91] innermost lazy narrowing, ....

G. Nadathur, B. Jayaraman. Towards a WAM Model for - Prolog. Proc. ICLP, MIT Press, 1180--1198, 1989.

....Y axis: run times in seconds) It has not been possible to compare our system with the other most recent attempts for implementing Prolog (Nadathur, Jayaraman, Felty) because of the lack of availability of a complete system. However, papers and technical reports by Nadathur and Jayaraman [35, 22, 21] show that their approach and ours are somewhat different and difficult to compare on the paper. In few words, they choose to base their design on a WAM augmented for handling Prolog s specifics. They represent terms and reduction in an environment based fashion. However, the differences may be ....

G. Nadathur and B. Jayaraman. Towards a WAM model for Prolog. In E.L. Lusk and R.A. Overbeek, editors, 1st North American Conf. Logic Programming, pages 1180--1198, MIT Press, 1989.

....the same functionality as is currently available in Isabelle, it is not likely to be nearly as efficient. This is due partly to the fact that a Prolog implementation implements a general purpose programming language. The development of more efficient implementations of Prolog is currently underway [1, 32, 9]. Another approach is to modify Prolog s depth first interpreter to use a different control strategy. For example, tacticals and interactive tactics could be implemented at the level of the metalanguage. This approach to control is more like that found in Isabelle. Universal quantification and ....

Gopalan Nadathur and Bharat Jayaraman. Towards a WAM model for Prolog. In Ewing Lusk and Ross Overbeek, editors, Proceedings of the North American Conference on Logic Programming, pages 1180--1198, October 1989.

.... means that the computation aborted. Length 32 64 128 256 512 1024 2048 4096 nrev 8.6 48.5 fnrev 6.2 20.6 79 338 1600 (1) list2flist .9 1.7 3.8 8.2 20 53 152 (2) list2flist .5 1 2.2 4. 9 10.7 27 89 Table 3: eLP times (s on sun4 with 14 Mb) Another implementation of Prolog is under study[8]. It will be WAM inspired, will use internally the de Bruijn s nameless representation of terms, and will be environment based. This is a radical difference with our implementation but it is difficult to foresee its consequences. Our optimizations will likely not apply to this scheme. For ....

G. Nadathur and B. Jayaraman. Towards a WAM model for Prolog. In E.L. Lusk and R.A. Overbeek, editors, 1st North American Conf. Logic Programming, pages 1180--1198, MIT Press, Cleveland, OH, 1989.

....implements L as well as the more general class of higher order hereditary Harrop formulas [22] the author has no experience in using an interpreter designed only to handle the L subset. See [5] for a functional programming implementations of interpreters for languages such as L and Prolog; see [23, 26] for discussions concerning the compilation of these languages. Below we present several examples of L programs written using the syntax of Prolog. The symbol = denotes oe, denotes its converse, a comma denotes conjunction, an infix occurrence of backslash denotes abstraction, and pi along ....

G. Nadathur and B. Jayaraman (1989). Towards a WAM Model for Prolog, North American Conference on Logic Programming, Cleveland, Ohio, edited by Ewing Lusk and Ross Overbeek, 1180 -- 1198.

....Nadathur in Standard Prolog. It was intended for experimental use and is very inefficient. Then, a more robust implementation has been done in Lisp (eLP, by the Ergo Project at CarnegieMellon University) The study of a compiled implementation of Prolog has been initiated by Nadathur and Jayaraman [57, 36] and is continuing with Nadathur, Kwon and Wilson [39] We know only progress reports about it, but no performance report. Finally, Felty and Gunther (Bell Labs) are working on another implementation in ML for extending the capability of ML as a meta language for automatic theorem proving. We ....

.... variables do not carry any type information. We know no publication on the implementation of either the original Prolog or eLP. So, we can only compare their behaviour with our implementation. The implementation choices of a third Prolog implementation are described by Nadathur and Jayaraman [57, 36]. We can compare the choices but not the behaviour because we have no access to a running implementation. These choices are very different from ours, so that an experimental comparison seems necessary. The main differences are an environment based reduction scheme, and a nameless approach. Another ....

G. Nadathur and B. Jayaraman. Towards a WAM model for Prolog. In E.L. Lusk and R.A. Overbeek, editors, 1st North American Conf. Logic Programming, pages 1180--1198, MIT Press, Cleveland, OH, 1989.

....Y axis: run times in seconds) It has not been possible to compare our system with the other most recent attempts for implementing Prolog (Nadathur, Jayaraman, Felty) because of the lack of availability of a complete system. However, papers and technical reports by Nadathur and Jayaraman [38, 23, 22] show that their approach and ours are somewhat different and difficult to compare on the paper. In few words, they choose to base their design on a WAM augmented for handling Prolog s specifics. They represent terms and reduction in an environment based fashion. However, the differences may be ....

G. Nadathur and B. Jayaraman. Towards a WAM model for Prolog. In E.L. Lusk and R.A. Overbeek, editors, 1st North American Conf. Logic Programming, pages 1180--1198, MIT Press, 1989.

....For example, compare the undecidability of higher order unification with the efficiency of first order unification. One way to recapture efficiency would be to compile or specialize the general search procedure to specific encoded logics. Only very preliminary work on this has been done [NJ89, MP93] 5 Representing Meta Theory Since logical frameworks are designed to express the language and inference rules of deductive systems at a very high level of abstraction, one rightly suspects that they should be amenable to an investigation of the meta theory of deductive systems. By far the ....

Gopalan Nadathur and Bharat Jayaraman. Towards a WAM model for Prolog. In Ewing Lusk and Ross Overbeek, editors, Proceedings of the North American Conference on Logic Programming, pages 1180--1198, Cleveland, Ohio, October 1989.

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Nadathur, G. and Jayaraman, B. Towards a WAM model for #Prolog. To appear in the Proceedings of the North American Conference on Logic Programming, MIT Press, 1989.

.... Clearly, the underlying machine model is explicitly manifest only in our work although many ideas relating to the compilation of the rst phase of simpli cation of disagreement sets receive a similar treatment in both contexts and and share also with an early presentation of some of our ideas [32]. Figure 6 complements our qualitative comparisons by presenting execution times for Prolog Mali and Teyjus on two di erent kinds of tasks. The naive reverse program is the one used in the earlier tests and, as such, provides a measure of behaviour over rstorder programs. The type inference ....

Gopalan Nadathur and Bharat Jayaraman. Towards a WAM model for Prolog. In Ewing Lusk and Ross Overbeek, editors, Proceedings of the North American Conference on Logic Programming, pages 1180-1198. MIT Press, October 1989.

....In providing a robust and ecient implementation for Prolog, three aspects that are novel to this language have to be dealt with: its higher order features, its new search primitives and its typing regimen. The ideas discussed in this paper complement work pertaining to the rst two aspects [10, 16, 17, 18, 21] and play a central role in an implementation that is being developed for this language. Despite the speci c context of interest, we focus in this paper on a (typed) rst order sublanguage of Prolog. We make this choice so as to simplify the presentation, the higher order features of the ....

....original motivation for this work was that of implementing the higher order language called Prolog. The ideas presented here are in fact employed more or less directly in an abstract machine that we have devised for this language that also incorporates devices for handling higher order features [16, 18, 21] and for implementing scoping constructs in logic programming [10, 17] An emulator for this machine is currently being implemented and we believe that this e ort will provide a practical vindication for the ideas described in this paper. 8 Acknowledgements We are grateful to Bharat Jayaraman ....

Gopalan Nadathur and Bharat Jayaraman. Towards a WAM model for Prolog. In Ewing Lusk and Ross Overbeek, editors, Proceedings of the North American Conference on Logic Programming, pages 1180-1198, Cleveland, Ohio, October 1989.

....monotonicity are more naturally expressed in terms of functions rather than predicates [25] 1.2. Implementation Issues The Warren Abstract Machine (WAM) 1, 35] designed by D.H.D. Warren, has proven to be a robust framework for implementing Prolog as well as several variants of the language [6, 11, 22, 33]. Our basic strategy is to extend the WAM with new instructions and run time structures in order to implement the new control regime as well as the new matching and unification operations of subset logic programs. It turns out that, even though the subset logic paradigm differs substantially from ....

G. Nadathur and B. Jayaraman, Towards a WAM Model for Prolog, Proc. North American Logic Programming Conference, pp. 1180--1198, MIT Press, 1989.

....In a similar vein, a richer term language like the one provided in [30] may also be considered as the basis for the data structures of Prolog. Among the practical questions, an important one that is being addressed is the description of an efficient implementation for a Prolog like language [26]. The key pursuit in this respect is to devise data structures for terms that will support reasonable implementations of the reduction mechanism of functional programming on the one hand, and of the unification and backchaining mechanisms of logic programming on the other. Another issue of ....

Nadathur, G. and Jayaraman, B. Towards a WAM model for Prolog. Proceedings of the North American Conference on Logic Programming, MIT Press, 1989, 1180 -- 1198.

....with the above strategy, this paper discusses implementation methods for one of the new features in Prolog, namely, the provision of implications and universal quantifiers in goals. It complements, in this respect, other work that we have done concerning the treatment of higher order aspects [19, 22] and types [10] The particular enrichment considered here is of interest in its own right; as one instance, permitting implications and universal quantifiers in goals provides the basis for scoping constructs in a language such as Prolog [2] From the perspective of an implementation, the ....

....the WAM. Our focus in most of this paper is in implementing a first order language whereas several examples presented in Section 2 use higher order features. The reason for this is twofold: a) implementing higher order aspects poses significant problems in its own right that we discuss elsewhere [19], and (b) the general methods for handling implications and universal quantifiers is in a certain sense independent of whether a first order or a higher order language is considered. This justification for the discrepancy notwithstanding, we outline in Section 8 extensions to our basic scheme that ....

[Article contains additional citation context not shown here]

Gopalan Nadathur and Bharat Jayaraman. Towards a WAM model for Prolog. In Ewing Lusk and Ross Overbeek, editors, Proceedings of the North American Conference on Logic Programming, pages 1180--1198, Cleveland, Ohio, October 1989.

....In providing a robust and efficient implementation for Prolog, three aspects that are novel to this language have to be dealt with: its higher order features, its new search primitives and its typing regimen. The ideas discussed in this paper complement work pertaining to the first two aspects [10, 16, 17, 18, 21] and play a central role in an implementation that is being developed for this language. Despite the specific context of interest, we focus in this paper on a (typed) first order sublanguage of Prolog. We make this choice so as to simplify the presentation, the higher order features of the ....

....original motivation for this work was that of implementing the higher order language called Prolog. The ideas presented here are in fact employed more or less directly in an abstract machine that we have devised for this language that also incorporates devices for handling higher order features [16, 18, 21] and for implementing scoping constructs in logic programming [10, 17] An emulator for this machine is currently being implemented and we believe that this effort will provide a practical vindication for the ideas described in this paper. 8 Acknowledgements We are grateful to Bharat Jayaraman ....

Gopalan Nadathur and Bharat Jayaraman. Towards a WAM model for Prolog. In Ewing Lusk and Ross Overbeek, editors, Proceedings of the North American Conference on Logic Programming, pages 1180--1198, Cleveland, Ohio, October 1989.

....that the notation for lambda terms developed there provides the basis for a satisfactory solution. Another problem concerns the implementation of higher order unification itself. One issue here is whether any aspect of this operation can be compiled. A start in this direction has been made in [18] for example, it is shown there that some of the first order aspects of this operation can be compiled but there is clearly much more that can be done. Another issue is that of dealing with the possibility for branching within the unification process. Mechanisms for accommodating this ....

....that some of the first order aspects of this operation can be compiled but there is clearly much more that can be done. Another issue is that of dealing with the possibility for branching within the unification process. Mechanisms for accommodating this possibility have been suggested in [18], but we suspect that these can be bettered, especially after experience is gained with an actual implementation of these mechanisms. Finally it is of interest to examine whether a recognition of special kinds of unification problems can be built into the unification procedure of [7] to improve ....

Gopalan Nadathur and Bharat Jayaraman. Towards a WAM model for Prolog. In Ewing Lusk and Ross Overbeek, editors, Proceedings of the North American Conference on Logic Programming, pages 1180--1198, Cleveland, Ohio, October 1989.

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