tailieunhanh - Báo cáo khoa học: "Underspecified Beta Reduction"

For ambiguous sentences, traditional semantics construction produces large numbers of higher-order formulas, which must then be -reduced individually. Underspecified versions can produce compact descriptions of all readings, but it is not known how to perform -reduction on these descriptions. We show how to do this using -reduction constraints in the constraint language for -structures (CLLS). They are based on dominance constraints (Marcus et al., 1983; Rambow et al., 1995) and extend them with parallelism (Erk and Niehren, 2000) and binding constraints. . | Underspecified Beta Reduction Manuel Bodirsky Katrin Erk Joachim Niehren Programming Systems Lab Saarland University D-66041 Saarbriicken Germany bodirsky erk niehren @ Abstract For ambiguous sentences traditional semantics construction produces large numbers of higher-order formulas which must then be d-reduced individually. Underspecified versions can produce compact descriptions of all readings but it is not known how to perform d-reduction on these descriptions. We show how to do this using -reduction constraints in the constraint language for A-structures CLLS . 1 Introduction Traditional approaches to semantics construction Montague 1974 Cooper 1983 employ formulas of higher-order logic to derive semantic representations compositionally then -reduction is applied to simplify these representations. When the input sentence is ambiguous these approaches require all readings to be enumerated and 3-reduced individually. For large numbers of readings this is both inefficient and unelegant. Existing underspecification approaches Reyle 1993 van Deemter and Peters 1996 Pinkal 1996 Bos 1996 provide a partial solution to this problem. They delay the enumeration of the readings and represent them all at once in a single compact description. An underspecification formalism that is particularly well suited for describing higher-order formulas is the Constraint Language for Lambda Structures CLLS Egg et al. 2001 Erk et al. 2001 . CLLS descriptions can be derived compositionally and have been used to deal with a rich class of linguistic phenomena Koller et al. 2000 Koller and Niehren 2000 . Alexander Koller Department of Computational Linguistics Saarland University D-66041 Saarbriicken Germany koller@ They are based on dominance constraints Marcus et al. 1983 Rambow et al. 1995 and extend them with parallelism Erk and Niehren 2000 and binding constraints. However lifting ổ-reduction to an operation on underspecified descriptions is not trivial and