<?xml version="1.0" standalone="yes"?>
<Paper uid="C96-1034">
  <Title>S I S Vr N VO CI VO Figure 3 Figure 4 s N Vr /\</Title>
  <Section position="2" start_page="0" end_page="194" type="abstr">
    <SectionTitle>
1 Lexicalized TAGs
</SectionTitle>
    <Paragraph position="0"> Lexicalized Tree Adjoining Grammar (LTAG) is a formalism integrating lexicon and grammar (Joshi, 87; Schabes et al., 88). It has both linguistic advantages (e.g elegant handling of unbounded dependencies and idioms) and computational advantages, particularly due to lexicalization (Schabes et al., 88). Linguists have developed over the years sizeable LTAG grammars, especially for English (XTAG group, 95; Abeill6 et al., 90) and French (Abeill6, 91).</Paragraph>
    <Paragraph position="1"> In this formalism, the lexical items are associated with the syntactic structures in which they can appear. The structures are lexicalized elementary trees, namely containing at least one lexical node at the frontier (called the anchor of the tree). The elementary tree describes the maximal projection of the anchor. So a verb-anchored tree has a sentential root. Features structures are associated with the trees, that are combined with substitution and adjunction. Adjunction allows the extended domain of locality of the formalism : all trees anchored by a predicate contains nodes for all its arguments.</Paragraph>
    <Paragraph position="2"> Such a lexicalized formalism needs a practical organization. LTAGs consist of a morphological lexicon, a syntactic qexicon of lemmas and a set of tree schemata, i.e. trees in which the lexical anchor is missing. In the syntactic lexicon, lemmas select the tree schemata they can anchor. When the grammar is used for parsing for instance, the words of the sentence to be parsed are associated with the relevant tree schemata to form complete lexicalized trees.</Paragraph>
    <Paragraph position="3"> Tile set of tree schemata forms the syntactic part of the grammar. The tree schemata selected by predicative items are grouped into families, and collectively selected. A tree family contains the different possible trees for a given canonical subcategorization (or predicate-argument structure). The arguments are numbered, starting at 0 for the canonical subject. Along with the &amp;quot;canonical&amp;quot; trees, a family contains the ones that would be transformationally related in a movement-base approach. These are first the trees where a &amp;quot;redistribution&amp;quot; of the syntactic function of the arguments has occurred, for instance the passive trees, or middle (for French) or dative shift (for English), leading to an &amp;quot;actual subcategorization&amp;quot; different from the canonical one. When such a redistribution occurs, the syntactic function of the arguments change (or the argument may not be realized anymore, as in the agentless passive). For instance, the subject of a passive tree is number l, and not 0 (figure 1). This is useful from a semantic point of view, in the case of selectional restrictions attached to the lexical items, or of a syntactic/semantic interface.</Paragraph>
    <Paragraph position="5"> passive for French 1 And secondly, a family may contain the trees with extracted argument (or cliticized in French). There are different types of trees for extraction. \]n the English grammar for instance, there are trees for wh-questions and trees for relative clauses (that are adjoined to NPs). In the French grammar there are also separate trees for cleft sentences with gaps in the clause, while the corresponding it-clefts are handled as relative clauses in the English grammar.</Paragraph>
    <Paragraph position="6">  symbol N is used for nominal phrases and nouns, the difference being expressed with a feature &lt;det&gt; (Abeill6, 91). we do not show the feature equations for the sake of clarity. For the French grammar, the average number of equations per tree is 12.  So a family contains all the schemata for a given canonical subcategorization. Yet, in the syntactic lexicon, a particular lemma may select a family only partially. For instance a lemma might select the transitive family, ruling out the passive trees.</Paragraph>
    <Paragraph position="7"> On the other hand, the features appearing in the tree schemata are common to every lemma selecting these trees. The idiosyncratic features (attached to the anchor or upper in the tree) are introduced in the syntactic lexicon.</Paragraph>
  </Section>
class="xml-element"></Paper>