Contents 1 Introduction 4 2 Tree Adjoining Grammar:An Overview 8 2.1 The Original TAG, and Why it is of Interest : : : : : : : : : : : : : : : : : 8 2.1.1 Factoring of Recursion and Cyclic Movement as Adjoining : : : : : : 10 2.1.2 The Derivation Tree : : : : : : : : : : : : : : : : : : : : : : : : : : : 12 2.1.3 Locality Constraints : : : : : : : : : : : : : : : : : : : : : : : : : : : 13 2.1.4 An Extended Domain of Locality : : : : : : : : : : : : : : : : : : : : 14 2.2 Multi-Component Extensions of TAG : : : : : : : : : : : : : : : : : : : : : 14 2.2.1 Tree-Local MCTAG : : : : : : : : : : : : : : : : : : : : : : : : : : : 14 2.2.2 Set-Local Multi-Component TAG : : : : : : : : : : : : : : : : : : : : 15 2.2.3 Non-Local Multi-Component TAG : : : : : : : : : : : : : : : : : : : 18 3 Some Problems for TAG 19 3.1 Romance Trouble : :

computation. This paper argues that such a characterization is correct, and that fundamental properties of grammar can and should be understood in terms of restrictions on the complexity of possible grammatical computation, when defined in terms of generative capacity. More specifically, the paper demonstrates that the computational restrictiveness imposed by Tree Adjoining Grammar provides important insights into the nature of human grammatical knowledge. 2 1

An NP-hardness proof for nonlocal MCTAG by Rambow and Satta (1992), based on Dahlhaus and Warmuth (1986), is extended to some restrictions of that formalism. It is found that there are NP-hard grammars among nonlocal MCTAGs even if the following restrictions are imposed: every tree in every tree set has a lexical anchor; every tree set may contain at most two trees; in every such tree set, there is a dominance link between the foot node of one tree and the root node of the other tree and this dominance link must be obeyed in the derived tree. This is the version of MCTAG used in Becker, Joshi, and Rambow (1991). The lexicalization restriction makes the grammar class NP-complete.

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Each grammar formalism specifies a domain of locality, i.e., a domain over which various dependencies (syntactic and semantic) can be specified. It turns about that the various properties of a formalism (syntactic, semantic, computational, and even psycholinguistic), follow, to a large extent, from the initial specification of the domain of locality. In this paper, we will briefly explore the extended domain of locality provided by the Lexicalized Tree-Adjoining Grammar (LTAG) in the context of some linguistic, computational, and psycholinguistic properties. This extended domain is achieved by specifying the elementary objects as structured objects (trees or directed acyclic graphs) instead of strings and two universal combining operations. Using lexicalized elementary structured objects it is possible to study directly many aspects of strong generative capacity which are more relevant to the linguistic descriptions.

It is well known that standard TAG cannot deal with certain instances of longdistance scrambling in German (Rambow, 1994). That CCG can deal with many instances of non-local scrambling in languages such as Turkish has previously been observed (e.g. by Hoffman (1995a) and Baldridge (2002)). We show here that CCG can derive German scrambling cases which are problematic for TAG, and give CCG analyses for other German constructions that require more expressive power than TAG provides. Such analyses raise the question of the linguistic significance

Abstract. We apply techniques of natural language processing to support the creation of special scrambled sentences that allow only specific word orders. The scrambled sentences are useful for students to practice their knowledge about grammars. It takes two steps to create a test item for scrambled-sentence tests. We create a set of grammatical alternative sentences from the target sentence, and make sure that students will rebuild the target sentence by pegging some of the words in the target sentence. The proposed methods can automatically and effectively peg words to single out a specific sentence from a set of sentences. We also employ the Stanford parser and propose a practical heuristic principle to help teachers exclude a potentially large number of alternative grammatical orderings of a set of words in the scrambled sentence.

Short-term forgetting in sentence comprehension: Crosslinguistic evidence from verb-final structures