It. Leermakers. How to cover a grammar. In 7th Annual Meeting of the ACL [1], pages 135-142.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....a polynomial time complexity however, because no packing takes place. A variant of Earley s algorithm discussed in [Leiss, 1990] also is very similar to GLC parsing although the top down nature of Earley s algorithm is pre served. GLC parsin has been rediscovered a number of times (e.g. in [Leermakers, 1989; Leermakers, 1992] Schabes, 1991] and [Perlin, 1991] but without any mention of the connection with LC parsing, which made the presentations unnecessarily difficult to understand. This also prevented discovery of a number of optimizations which are obvious from the viewpoint of left corner ....

It. Leermakers. How to cover a grammar. In 7th Annual Meeting of the ACL [1], pages 135-142.

.... OPTIMAL TABULAR PARSING ALGORITHM Mark Jan Nederhof University of Nijmegen, Department of Computer Science Toernooiveld, 6525 ED Nijmegen, The Netherlands markj ancs. kun. nl Abstract In this paper we relate a number of parsing algorithms which have been developed in very different areas of parsing theory, and which include deterministic algorithms, tabular algorithms, and a parallel algorithm. We show that these ....

.... OPTIMAL TABULAR PARSING ALGORITHM Mark Jan Nederhof University of Nijmegen, Department of Computer Science Toernooiveld, 6525 ED Nijmegen, The Netherlands markj ancs. kun. nl Abstract In this paper we relate a number of parsing algorithms which have been developed in very different areas of parsing theory, and which include deterministic algorithms, tabular algorithms, and a parallel algorithm. We show that these ....

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R. Leermakers. How to cover a grammar. In 7th Annual Meeting of the ACL, 135-142, 1989.

....and A fl q 2, which reduces nondeterminism. We may however also specify an algorithm which succeeds in simultaneously processing all common infixes, irrespective of whether the left hand sides of the corresponding rules are the same. This algorithm is inspired by extended LR (ELR) parsing [12, 7] for extended context free grammars (where right hand sides consist of regular expressions over V) By analogy, it will be called extended HI (EHI) parsing. This algorithm uses yet another kind of item, viz. of the form [i,k, A,A, Ar) m,j] where there exists at least one rule A a 7 ....

R. Leermakers. How to cover a grammar. In 7th Annual Meeting of the ACL, pages 135-142, June 1989.

....oe. The order is actually a partial pre order (we may have t t 0 and t 0 t and t 6= t 0 ) with an associated equivalence relation j (variance 2 Actually dotted rules may be seen as non terminals obtained in an implicit construction that turns context free grammars into Chomsky normal form [10]. 10 relation) defined by t j r iff t r and r t. Substitutions are also partially (pre) ordered: oe ae iff for all terms t, toe tae. Renaming a term t with fresh variables returns a new term t 0 variant of t (t j t 0 ) that shares no common variable with t. When successful, the ....

Ren'e Leermakers. How to cover a grammar. In Proc. of the 27th Annual Meeting of the Association for Computational Linguistics, pages 135--142. ACL, June 1989. 37

....Lang (1974) and Billot and Lang (1989) the construction of pushdown automata from grammars and the simulation of these automata by means of tabulation yield different tabular algorithms for different such constructions. Another example, on which our presentation is based, was first suggested by Leermakers (1989): a grammar is first transformed and then a standard tabular algorithm along withsome filtering condition is applied using the transformed grammar. In our case, the transformation and the subsequent application of the tabular algorithm result in a new form of tabular LR parsing. Our method is more ....

....transformed by the transformation two given by Nederhof and Satta (1994) 2 3.2.5 The algorithm This section presents a tabular LR parser, which is our main result. The parser is derived from the 2LR automata introduced in the previous section. Following the general approach presented by Leermakers (1989), we simulatecomputations of these devices using a tabular method, a grammar transformation and a filtering function. We make use of a tabular parsing algorithm which is basically an asynchronous version of the CYK algorithm, as presented by Harrison (1978) extended to productions of the forms A ....

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Leermakers, Rene. 1989. How to cover a grammar. In 27th Annual Meeting of the Association for Computational Linguistics, pages 135--142, Vancouver.

....relationship between certain grammar transformations and certain parsers, such as that of Graham et al. 1980) discussed in Section 2.7.5 and Appendix 2 B.1. While the relationship between grammar transformations and parsers is already known in the literature on covering grammars (Nijholt, 1980; Leermakers, 1989), our treatment is clearer, because we use the same machinery for specifying both the transformations and the parsers, allowing commonalities to be expressed in the same way in both cases. There are three steps to the CNF transformation: removal of epsilon productions; removal of unary ....

R. Leermakers. 1989. How to cover a grammar. In Proceedings of the 27th Annual Meeting of the ACL, pages 135--142, Vancouver.

....requires a CF grammar expressed in Chomsky Normal Form (CNF) 5 , and has a worst case time complexity of O(n 3 ) where n is the length of the input 6 . Earley (1970) describes a CF parsing algorithm which is not restricted to CNF grammars but nevertheless also has cubic complexity. Leermakers (1989) shows that it achieves this by implicitly using a 2 form version of the grammar at parse time (i.e. each rule having at most two daughters) dotted rules (section 4.1.2) being new non11 4 A parser returns an analysis (or set of analyses) for a grammatical input, whereas a recogniser only ....

Leermakers, R. (1989) "How to cover a grammar." In Proceedings of the 27th Meeting of the Association for Computational Linguistics , Vancouver, Canada, 135--142.

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Leermakers, R. 1989. How to cover a grammar. In Proc. 27th Annual Meeting of the ACL, 135--142. Vancouver, British Columbia: ACL.

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