I wish to thank Bonnie Webber. Without her patience and her seemingly endless depths of insight, I might never have completed this thesis. I am enormously grateful for her guidance. I also owe many thanks to Ellen Prince. She is an intellectual leader at Penn who has helped many, including me, find a way through the jungle of discourse analysis. I am indebted to every professor who has taught me. Special thanks to Robin Clark for being a member of my dissertation committee. I am very lucky to have worked with Aravind Joshi. He is a continual source of knowledge in the DLTAG meetings. The field of computational linguistics has already benefited from his sentencelevel work; I fully expect he and Bonnie will produce similarly useful results with DLTAG. Also in DLTAG, Eleni Miltsakaki and Rashmi Prasad, and later Cassandre Creswell and Jason Teeple all provided stimulation and solace. Their great company and great effort on DLTAG projects taught me to appreciate how much can be done when minds work together. I look forward to the chance to work with them in the future. I am also thankful to Martha Palmer, Paul Kingsbury, and Scott Cotton for allowing me to work with them on the Propbank project and supplement both my income and my work in discourse. On a personal note, the Forbes, Finley, and Riley families deserve thanks for giving me love and diversion and balance and talking me through my education. Most of all, thanks to Enrico Riley, for being everything to me.

D-LTAG is a discourse-level extension of lexicalized tree-adjoining grammar (LTAG), in which discourse syntax is projected by different types of discourse connectives and discourse interpretation is a product of compositional rules, anaphora resolution, and inference. In this paper, we present a D-LTAG extension of ongoing work on an LTAG syntax-semantic interface. First, we show how predicate-argument semantics are computed for standard, ‘structural ’ discourse connectives. These are connectives that retrieve their semantic arguments from their D-LTAG syntactic tree. Then we focus on discourse connectives that occur syntactically as (usually) fronted adverbials. These connectives do not retrieve both their semantic arguments from a single D-LTAG syntactic tree. Rather, their predicate-argument structure and interpretation distinguish them from structural connectives as well as from other adverbials that do not function as discourse connectives. The unique contribution of this paper lies in showing how compositional rules and anaphora resolution interact within the D-LTAG syntaxsemantic interface to yield their semantic interpretations, with multi-component syntactic trees sometimes being required. 1

al., 1995) point out the differences between TAG derivation structures and semantic or predicate- argument dependencies, and Joshi and VijayShanker (Joshi and Vijay-Shanker, 1999) de- scribe a monotonic compositional semantics based on attachment order that represents the desired dependencies of a derivation without underspecifying predicate-argument relationships at any stage. In this paper, we apply the Joshi and Vijay-Shanker conception of compositional semantics to the problem of preserving semantic dependencies in Synchronous TAG translation (Shieber and Schabes, 1990; Abeill6 et al., 1990). In particular, we describe an algorithm to obtain the semantic dependencies on a TAG parse forest and construct a target derivation forest with isomorphic or locally non-isomorphic dependencies in O(n 7) time.

This article addresses the problem that the expressive power of tree-adjoining grammars (TAGs) is too limited to deal with certain syntactic phenomena, in particular, with scrambling in freeword-order languages. The TAG variants proposed so far in order to account for scrambling are not entirely satisfying. Therefore, the article introduces an alternative extension of TAG that is based on the notion of node sharing, so-called (restricted) tree-local multicomponent TAG with shared nodes (RSN-MCTAG). The analysis of some German scrambling data is sketched in order to show that this TAG extension can deal with scrambling. Then it is shown that for RSN-MCTAGs of a specific type, equivalent simple range concatenation grammars can be constructed. As a consequence, these RSN-MCTAGs are mildly context-sensitive and in particular polynomially parsable. These specific RSN-MCTAGs probably can deal not with all scrambling phenomena, but with an arbitrarily large subset.

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This paper develops a framework for TAG (Tree Adjoining Grammar) semantics that brings together ideas from different recent approaches. Then, within this framework, an analysis of scope is proposed that accounts for the different scopal properties of quantifiers, adverbs, raising verbs and attitude verbs. Finally, including situation variables in the semantics, different situation binding possibilities are derived for different types of quantificational elements. 1

We present a class-based approach to building a verb lexicon that makes explicit the close relation between syntax and semantics for Levin classes. We have used a Lexicalized Tree Adjoining Grammar to capture the syntax associated with each verb class and have added semantic predicates to each tree, which allow for a compositional interpretation. 1. Introduction We describe a computational verb lexicon called VerbNet which utilizes Levin verb classes (Levin, 1993) to systematically construct lexical entries. We have used Lexicalized Tree Adjoining Grammar (LTAG) (Joshi, 1985; Schabes, 1990) to capture the syntax associated with each verb class, and have added semantic predicates. We also show how regular extensions of verb meaning can be achieved through the adjunction of particular syntactic phrases. We base these regular extensions on intersective Levin classes, a fine-grained variation on Levin classes, as a source of semantic components associated with specific adjuncts (Dang et ...

I show how a conversational process that takes simple, intuitively meaningful steps may be understood as a sophisticated computation that derives the richly detailed, complex representations implicit in our knowledge of language. To develop the account, I argue that natural language is structured in a way that lets us formalize grammatical knowledge precisely in terms of rich primitives of interpretation. Primitives of interpretation can be correctly viewed intentionally, as explanations of our choices of linguistic actions; the model therefore fits our intuitions about meaning in conversation. Nevertheless, interpretations for complex utterances can be built from these primitives by simple operations of grammatical derivation. In bridging analyses of meaning at semantic and symbol-processing levels, this account underscores the fundamental place for computation in the cognitive science of language use.

We explore some properties of the synchronous formalism introduced in Dras (1999), showing that it handles an interaction, noted in Schuler (1999), between bridge and raising verbs which is problematic for synchronous TAG. We also show that it has greater formal power than synchronous TAG and discuss its computational complexity. 1.

In this paper we propose a syntactic and semantic analysis of complex questions. We consider questions involving pied piping and stranding and we propose elementary trees and semantic representations that allow to account for both constructions in a uniform way.