A simple reconstruction of GPSG

Like most linguistic theories, the theory of generalized phrase structure grammar (GPSG) has described language axiomatically, that is, as a set of universal and language-specific constraints on the well-formedness of linguistic elements of some sort. The coverage and detailed analysis of English grammar in the ambitious recent volume by Gazdar, Klein, Pullum, and Sag entitled Generalized Phrase Structure Grammar are impressive, in part because of the complexity of the axiomatic system developed by the authors. In this paper. We examine the possibility that simpler descriptions of the same theory can be achieved through a slightly different, albeit still axiomatic, method. Rather than characterize the well-formed trees directly, we progress in two stages by procedurally characterizing the well-formedness axioms themselves, which in turn characterize the trees.Engineering and Applied Science

Type-driven natural language analysis

The purpose of this thesis is in showing how recent developments in logic programming can be exploited to encode in a computational environment the features of certain linguistic theories. We are in this way able to make available for the purpose of natural language processing sophisticated capabilities of linguistic analysis directly justified by well developed grammatical frameworks. More specifically, we exploit hypothetical reasoning, recently proposed as one of the possible directions to widen logic programming, to account for the syntax of filler-gap dependencies along the lines of linguistic theories such as Generalized Phrase Structure Grammar and Categorial Grammar. Moreover, we make use, for the purpose of semantic analysis of the same kind of phenomena, of another recently proposed extension, interestingly related to the previous one, namely the idea of replacing first-order terms with the more expressive λ-terms of λ-Calculus

What Does a Grammar Formalism Say About a Language?

Over the last ten or fifteen years there has been a shift in generative linguistics away from formalisms based on a procedural interpretation of grammars towards constraint-based formalisms—formalisms that define languages by specifying a set of constraints that characterize the set of well-formed structures analyzing the strings in the language. A natural extension of this trend is to define this set of structures model-theoretically—to define it as the set of mathematical structures that satisfy some set of logical axioms. This approach raises a number of questions about the nature of linguistic theories and the role of grammar formalisms in expressing them. We argue here that the crux of what theories of syntax have to say about language lies in the abstract properties of the sets of structures they license. This is the level that is most directly connected to the empirical basis of these theories and it is the level at which it is possible to make meaningful comparisons between the approaches. From this point of view, grammar formalisms, or (formal frameworks) are primarily means of presenting these properties. Many of the apparent distinctions between formalisms, then, may well be artifacts of their presentation rather than substantive distinctions between the properties of the structures they license. The model-theoretic approach offers a way in which to abstract away from the idiosyncrasies of these presentations. Having said that, we must distinguish between the class of sets of structures licensed by a linguistic theory and the set of structures licensed by a specific instance of the theory—by a grammar expressing that theory. Theories of syntax are not simply accounts of the structure of individual languages in isolation, but rather include assertions about the organization of the structure of human languages in general. These universal aspects of the theories present two challenges for the model-theoretic approach. First, they frequently are not properties of individual structures, but are rather properties of sets of structures. Thus, in capturing these model-theoretically one is not defining sets of structures but is rather defining classes of sets of structures; these are not first order properties. Secondly, the universal aspects of linguistic theories are frequently not explicit, but are consequences of the nature of the formalism that embodies the theory. In capturing these one must develop an explicit axiomatic treatment of the formalism. This is both a challenge and a powerful beneft of the approach. Such re-interpretations tend to raise a variety of issues that are often overlooked in the original formalization. In this report we examine these issues within the context of a model-theoretic reinterpretation of Generalized Phrase-Structure Grammar. While there is little current active research on GPSG, it provides an ideal laboratory for exploring these issues. First, the formalism of GPSG is expressly intended to embody a great deal of the accompanying linguistic theory. Thus it provides a variety of opportunities for examining principles expressed as restrictions on the formalism from a model-theoretic point of view. At the same time, the fact that these restrictions embody universal grammar principles provides us with a variety of opportunities to explore the way in which the linguistic theory expressed by a grammar can transcend the mathematical theory of the structures it licenses. Finally, GPSG, although defined declaratively, is a formalism with restricted generative capacity, a characteristic more typical of the earlier procedural formalisms. As such, one component of the theory it embodies is a claim about the language-theoretic complexity of natural languages. Such claims are difficult to establish for any of the constraint-based approaches to grammar. We can show, however, that the class of sets of trees that are definable within the logical language we employ in reformalizing GPSG is nearly exactly the class of sets of trees definable within the basic GPSG formalism. Thus we are able to capture the language-theoretic consequences of GPSGs restricted formalism by employing a restricted logical language

La linguistique au contact de l'informatique : de la construction des grammaires aux grammaires de construction

National audienceLes auteurs proposent un essai d'histoire rationnelle d'un aspect du programme génératif dans sa relation à l'informatique, celui qui va de la définition de la notion de grammaire par Chomsky, et en particulier de la caractérisation mathématique des grammaires possibles (la linguistique algébrique), à la conception de grammaires multidimensionnelles qui trouvent dans les systèmes de représentation des connaissances leur fondation formelle. Les auteurs distinguent trois moments : (a) l'émergence du programme génératif et de la notion de grammaire générative ; (b) le mouvement de réforme qui se cristallise dans le refus de la forme transformationnelle de la grammaire et qui voit l'invention de nombreux nouveaux formalismes qui auront tous la caractéristique d'être déclaratifs ; (c) le développement des grammaires multidimensionnelles qui sont chargées d'intégrer les analyses des dimensions formelles (syntaxe et phonologie) et non formelles (sémantique, pragmatique) des langues

Classification-based phrase structure grammar: an extended revised version of HPSG

This thesis is concerned with a presentation of Classification -based Phrase Structure Grammar (or cPSG), a grammatical theory that has grown out of extensive revisions of, and extensions to, HPSG. The fundamental difference between this theory and HPSG concerns the central role that classification plays in the grammar: the grammar classifies strings, according to their feature structure descriptions, as being of various types. Apart from the role of classification, the theory bears a close resemblance to HPSG, though it is by no means a direct translation, including numerous revisions and extensions. A central goal in the development of the theory has been its computational implementation, which is included in the thesis.The presentation may be divided into four parts. In the first, chapters 1 and 2, we present the grammatical formalism within which the theory is stated. This consists of a development of the notion of a classificatory system (chapter 1), and the incorporation of hierarchality into that notion (chapter 2).The second part concerns syntactic issues. Chapter 3 revises the HPSG treatment of specifiers, complements and adjuncts, incorporating ideas that specifiers and complements should be distinguished and presenting a treatment of adjuncts whereby the head is selected for by the adjunct. Chapter 4 presents several options for an account of unbounded dependencies. The accounts are based loosely on that of GPSG, and a reconstruction of GPSG's Foot Feature Principle is presented which does not involve a notion of default. Chapter 5 discusses coordination, employing an extension of Rounds- Kasper logic to allow a treatment of cross -categorial coordination.In the third part, chapters 6, 7 and 8, we turn to semantic issues. We begin (Chapter 6) with a discussion of Situation Theory, the background semantic theory, attempting to establish a precise and coherent version of the theory within which to work. Chapter 7 presents the bulk of the treatment of semantics, and can be seen as an extensive revision of the HPSG treatment of semantics. The aim is to provide a semantic treatment which is faithful to the version of Situation Theory presented in Chapter 6. Chapter 8 deals with quantification, discussing the nature of quantification in Situation Theory before presenting a treatment of quantification in CPSG. Some residual questions about the semantics of coordinated noun phrases are also addressed in this chapter.The final part, Chapter 9, concerns the actual computational implementation of the theory. A parsing algorithm based on hierarchical classification is presented, along with four strategies that might be adopted given that algorithm. Also discussed are some implementation details. A concluding chapter summarises the arguments of the thesis and outlines some avenues for future research

Clause union and verb raising phenomena in German

In this paper we discuss a class of constructions in German syntax which have been known as coherent infinitive, clause union or verb raising constructions. These data run against the predictions of strictly configurational theories by apparently having a syntactic structure where the subcategorization frames of two or more verbal heads are merged into one. Thus, in addition to a fully bi-clausal structure with two clearly separated verbal heads, we also have to envisage the case where a verb is apparently raised from an embedded to form a verb cluster together with its governing verb, while the sets of their arguments are merged into a single set, representing the case of clause union. In addition, there are constructions where there is no evidence for clause union, but where one could nevertheless argue for the formation of a verb cluster. We investigate these data by looking at a series of constructions which bear evidence on the issue. Among these are extraposition, which appears a reliable test for nonobligatory verb raising; subjectless constructions, which are possible only as the complements of so-called raising verbs but not of control verbs; S-pronominalization, which seems to be limited to equi-verbs; scrambling and long reflexivization, which we can take as evidence for clause union; the scope of adjuncts and negation which argues in favour of verb raising, but does not necessarily presuppose clause union; and finally certain topicalization phenomena which appear to violate almost any of the generalizations set up so far by configurational theories

A formal theory of word order: a case study in West Germanic

This thesis has three primary goals . The first goal is to provide a treatrnent of bounded discontinuous constituency and word order in genera! and semi-free word order in particular. Bounded discontinuous constituency is taken to mean the kind of category-bounded discontinuity typically found in the German Mit­telfeld and in Dutch "cross-serial'' dependency constructions. It does not mean unbounded dependencies such as wh-movement. The second goal is to provide an alternative account of cross-linguistic variation in word order (particularly in West Germanic) to the Principles and Parameters approach of Government and Binding Theory. The third goal is to formalise the account in a single homogeneous logical formalism which is not based on rewrite rules or other formal language theoretic machinery