Algorithm for grammars

Lecture Compiler construction: Lesson 23 - Sohail Aslam. The main topics covered in this chapter include: the number of potential handles for the grammar simply the sum of the lengths of the right-hand side of all the productions; the number of complete handles is simply the number of productions;...

35p youzhangjing_1909 28-04-2022 16 1   Download

In this paper an algorithm for the convex polygon triangulation based on the reverse Polish notation is proposed. The formal grammar method is used as the starting point in the investigation. This idea is "translated" to the arithmetic expression field enabling application of the reverse Polish notation method.

7p vinguyentuongdanh 20-12-2018 25 1   Download

In computer science, a recursive descent parser is a kind of top-down parser built from a set of mutually recursive procedures (or a non-recursive equivalent) where each such procedure usually implements one of the productions of the grammar. In this lecture will introduce recursive descent (RD) parser. Inviting you to refer for more detail.

22p youcanletgo_02 07-01-2016 38 2   Download

This paper defines a language Z~ for specifying LFG grammars. This enables constraints on LFG's composite ontology (c-structures synchronised with fstructures) to be stated directly; no appeal to the LFG construction algorithm is needed. We use f to specify schemata annotated rules and the LFG uniqueness, completeness and coherence principles. Broader issues raised by this work are noted and discussed.

6p buncha_1 08-05-2013 40 2   Download

We report grammar inference experiments on partially parsed sentences taken from the Wall Street Journal corpus using the inside-outside algorithm for stochastic context-free grammars. The initial grammar for the inference process makes no ,assumption of the kinds of structures and their distributions. The inferred grammar is evaluated by its predicting power and by comparing the bracketing of held out sentences imposed by the inferred grammar with the partial bracketings of these sentences given in the corpus.

7p buncha_1 08-05-2013 51 3   Download

We show how techniques known from generMized LR parsing can be applied to leftcorner parsing. The ~esulting parsing algorithm for context-free grammars has some advantages over generalized LR parsing: the sizes and generation times of the parsers are smaller, the produced output is more compact, and the basic parsing technique can more easily be adapted to arbitrary context-free grammars. The algorithm can be seen as an optimization of algorithms known from existing literature.

10p buncha_1 08-05-2013 34 2   Download

This paper presents a method for parsing associative Lambek grammars based on graphtheoretic properties. Connection graphs, which are a simplified version of proof-nets, are actually a mere conservative extension of the earlier method of syntactic connexion, discovered by Ajduckiewicz [1935]. The method amounts to find alternating spanning trees in graphs. A sketch of an algorithm for finding such a tree is provided. Interesting properties of time-complexity for this method are expected.

8p buncha_1 08-05-2013 47 1   Download

Attribute grammars are an elegant formalization of the augmented context-free grammars characteristic of most current natural language systems. This paper presents an extension of Earley's algorithm to Knuth's attribute grammars, considering the case of S-attributed grammars. For this case, we study the conditions on the underlying base grammar under which the extended algorithm may be guaranteed to terminate. Finite partitioning of attribute domains is proposed to guarantee the termination of the algorithm, without the need for any restrictions on the context-free base. ...

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In this paper M-grammars t h a t are used in the Rosetta translation system will be looked at as the specification of a t t r i b u t e grammars. We will show t h a t the a t t r i b u t e evaluation order is such t h a t instead of the special-purpose parsing and generation algorithms introduced for M-grammars in Appelo et al.(1987), also Earley-like context-free parsing and ordinary generation strategies can be used. Furthermore, it is illustrated t h a t the a t t r i...

6p buncha_1 08-05-2013 46 1   Download

This paper describes a classical logic for attribute-value (or feature description) languages which ate used in urfification grammar to describe a certain kind of linguistic object commonly called attribute-value structure (or feature structure). Tile algorithm which is used for deciding satisfiability of a feature description is based on a restricted deductive closure construction for sets of literals (atomic formulas and negated atomic formulas). In contrast to the Kasper/Rounds approach (cf.

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Natural language systems based on Categorial Unification Grammar (CUG) have mainly employed bottomup parsing algorithms for processing. Conventional prediction techniques to improve the efficiency of the • parsing process, appear to fall short when parsing CUG. Nevertheless, prediction seems necessary when parsing grammars with highly ambiguous lexicons or with noncanonical categorial rules. In this paper we present a lexicalist prediction technique for CUG and show thai this may lead to considerable gains in efficiency for both bottom-up and top-down parsing. ...

6p buncha_1 08-05-2013 51 1   Download

This paper proposes an LR parsing algorithm modified for grammars with feature-based categories. The proposed algorithm does not instantiate categories during preprocessing of a grammar as proposed elsewhere. As a result, it constructs a minimal size of GOTO/ACTION table and eliminates the necessity of search for GOTO table entries during parsing.

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In this paper a bidirectional parser for Lexicalized Tree Adjoining Grammars will be presented. The algorithm takes advantage of a peculiar characteristic of Lexicalized TAGs, i.e. that each elementary tree is associated with a lexical item, called its anchor. The algorithm employs a mixed strategy: it works bottom-up from the lexical anchors and then expands (partial) analyses making top-down predictions.

6p buncha_1 08-05-2013 50 2   Download

We present an algorithm for the generation of sentences from the semantic representations of Unification Categorial Grammar. We discuss a variant of Shieber's semantic monotonicity requirement and its utility in our algorithm. We indicate how the algorithm may be extended to other grammars obeying the same requirement. Appendices contain a full listing of the program and a trace of execution of the algorithm.

8p buncha_1 08-05-2013 33 1   Download

This paper shows how higher levels of generalization can be introduced into unification grammars by exploiting methods for typing grammatical objects. We discuss the strategy of using global declarations to limit possible linguistic structures, and sketch a few unusual aspects of our typechecking algorithm. We also describe the sort system we use in our semantic representation language and illustrate the expressive power gained by being able to state global constraints over these sorts.

8p buncha_1 08-05-2013 37 1   Download

We investigate the problem of determining a compact underspecified semantical representation for sentences that may be highly ambiguous. Due to combinatorial explosion, the naive method of building semantics for the different syntactic readings independently is prohibitive. We present a method that takes as input a syntactic parse forest with associated constraintbased semantic construction rules and directly builds a packed semantic structure. The algorithm is fully implemented and runs in O(n4log(n)) in sentence length, if the grammar meets some reasonable 'normality' restrictions. ...

8p bunthai_1 06-05-2013 53 3   Download

We present an algorithm for simultaneously constructing both the syntax and semantics of a sentence using a Lexicalized Tree Adjoining Grammar (LTAG). This approach captures naturally and elegantly the interaction between pragmatic and syntactic constraints on descriptions in a sentence, and the inferential interactions between multiple descriptions in a sentence. At the same time, it exploits linguistically motivated, declarative specifications of the discourse functions of syntactic constructions to make contextually appropriate syntactic choices. ...

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Valiant showed that Boolean matrix multiplication (BMM) can be used for CFG parsing. We prove a dual result: CFG parsers running in time O([Gl[w[3-e) on a grammar G and a string w can be used to multiply m x m Boolean matrices in time O(m3-e/3). In the process we also provide a formal definition of parsing motivated by an informal notion due to Lang. Our result establishes one of the first limitations on general CFG parsing: a fast, practical CFG parser would yield a fast, practical BMM algorithm, which is not believed to exist. 1 Introduction The standard method...

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This report describes the development of a parsing system for written Swedish and is focused on a grammar, the main component of the system, semiautomatically extracted from corpora. A cascaded, finite-state algorithm is applied to the grammar in which the input contains coarse-grained semantic class information, and the output produced reflects not only the syntactic structure of the input, but grammatical functions as well. The grammar has been tested on a variety of random samples of different text genres, achieving precision and recall of 94.62% and 91.

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In this paper we study spectral learning methods for non-deterministic split headautomata grammars, a powerful hiddenstate formalism for dependency parsing. We present a learning algorithm that, like other spectral methods, is efficient and nonsusceptible to local minima. We show how this algorithm can be formulated as a technique for inducing hidden structure from distributions computed by forwardbackward recursions.

11p bunthai_1 06-05-2013 49 3   Download