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Báo cáo khoa học: "A UNIFICATION-BASED SEMANTIC INTERPRETATION FOR COORDINATE CONSTRUCTS"
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This paper shows that a first-order unificationbased semantic interpretation for various coordinate constructs is possible without an explicit use of lambda expressions if we slightly modify the standard Montagovian semantics of coordination. This modification, along with partial execution, completely eliminates the lambda reduction steps during semantic interpretation. | A UNIFICATION-BASED SEMANTIC INTERPRETATION FOR COORDINATE CONSTRUCTS Jong c. Park University of Pennsylvania Computer and Information Science 200 South 33rd Street Philadephia PA 19104-6389 USA Internet parkQlinc. cis.upenn. edu Abstract This paper shows that a first-order unificationbased semantic interpretation for various coordinate constructs is possible without an explicit use of lambda expressions if we slightly modify the standard Montagovian semantics of coordination. This modification along with partial execution completely eliminates the lambda reduction steps during semantic interpretation. 1 Introduction Combinatory Categorial Grammar CCG has been offered as a theory of coordination in natural language Steedman 1990 . It has usually been implemented in languages based on first order unification. Moore 1989 however has pointed out that coordination presents problems for first-order unification-based semantic interpretation. We show that it is possible to get over the problem by compiling the lambda reduction steps that are associated with coordination in the lexicon. We show how our first-order unification handles the following examples of coordinate constructs. 1.1 Harry walks and every farmer walks. 1.2 A farmer walks and talks. 1.3 A farmer and every senator talk. 1.4 Harry finds and a woman cooks a mushroom. 1.5 Mary gives every dog a bone and some policeman a flower. We will first start with an illustration of why standard Montagovian semantics of coordination cannot be immediately rendered into a first-order unification strategy. The lexicon must contain multiple entries for the single lexical item and since only like categories are supposed to conjoin. For example the lexical entry for and in 1.1 specifies the constraint that the lexical item should expect on both sides sentences to give a sentence. Moore 1989 predicts that a unification-based semantic interpretation for sentences which involve for example noun phrase coordination won t be .