Abstract not found

We describe a new framework for dependency grammar, with a modular decomposition of immediate dependency and linear precedence. Our approach distinguishes two orthogonal yet mutually constraining structures: a syntactic dependency tree and a topological dependency tree. The syntax tree is nonprojective and even non-ordered, while the topological tree is projective and partially ordered. 1

Abstract. In this paper I discuss several possible analyses for constituent order in German. Approaches that assume continuous constituents are compared with an approach that assumes discontinuous constituents. I will show that certain proposals that have been made to analyze constituent order are either not adequate or cannot be implemented with currently available systems. For the proposals that can be implemented I will discuss the amount of work a parser has to do. I then compare two implementations of larger fragments of German: the Verbmobil grammar and the Babel grammar. It is shown that the amount of work to be done to parse the Verbmobil grammar is significantly higher than the work that has to be done parsing with the Babel grammar. Key words: German, HPSG, implementation, linearization, parsing 1.

ABSTRACT: Trees with labeled edges have widespread applicability, for example for the representation of dependency syntax trees. Given a fixed number of nodes and constraints on how edges may be drawn between them, the task of finding solution trees is known as a configuration problem. In this paper, we formalize the configuration problem of labeled trees and argue that it can be regarded as a constraint satisfaction problem which can be solved directly and efficiently by constraint propagation. In particular, we derive and prove correct a formulation of dependency parsing as a constraint satisfaction problem. Our approach, based on constraints on finite sets and a new family of ‘selection ’ constraints, is especially well-suited for the compact representation and efficient processing of ambiguity. We address various issues of interest to the computational linguist such as lexical ambiguity, structural ambiguity, valency constraints, grammatical principles, and linear precedence. Finally we turn to the challenge of efficient processing and characterize the services expected of a constraint programming system: we define a formal constraint language and specify its operational semantics with inference rules of propagation and distribution. This framework generalizes our presentation of immediate syntactic dependence for dependency parsing [4] and extends naturally to our corresponding treatment of linear precedence [6] based on a notion of topological rather than syntactic dependencies.

Theoretical linguistics requires example sentences both as empirical basis for the development of theories and as counterexamples to previous generalizations. In addition to obtaining such examples by introspection, electronic corpora can be used to search for examples which are relevant for a particular theoretical issue. This second option is only rarely used in generative linguistics, possibly since it is not fully appreciated that such a use of corpora is in principle independent of the fundamental methodological issues separating empiricists and rationalists. This paper illustrates with examples from the syntax of German how searching in corpora can help find theoretically relevant examples. Such examples are particularly interesting in that they exhibit a wide variation of potentially relevant parameters. The case studies highlight how linguistic terminology used to single out the relevant phenomenon can be reconstructed in terms of the empirical properties which are accessible directly or through annotations in a corpus. To appear in Lingua.

We propose a lexicalized formulation of dependency grammar that addresses both immediate dependence and linear precedence. Our approach distinguishes two orthogonal, yet mutually constraining dependency trees: an ID tree of syntactic dependencies and a LP tree of topological dependencies. The ID tree is non-ordered, non-projective and its edges are labeled by grammatical functions. The LP tree is ordered and projective and expresses licensed linearizations; its edges are labeled by topological fields. The LP tree can be regarded as deriving from the ID tree through a process of emancipation controlled by lexicalized constraints and principles. In the present article, we formalize valid ID/LP analyses and show how they can be characterized as the solutions of a constraint satisfaction problem. The latter can be solved by constraint programming and forms the basis of our implementation.

Abstract not found

Abstract not found

This paper introduces the notion of tree tuples to MCTAG, an extension of Tree Adjoining Grammar (TAG). Using tuples and node sharing we can provide an empirically broad and linguistically sound analysis of coherent constructions and scrambling in German, without the compulsive use of traces or the additional descriptive means in former MCTAG approaches.

This paper addresses the issue of embedded zu-infinitival clauses in German from the