tailieunhanh - Báo cáo khoa học: "O PARSING PREFERENCES"

It is argued that syntactic p r e f e r e n c e principles such as Right A s s o c i a t i o n and Minimal Attachment are unsatisfactory as usually formulated. Among the difficulties are: (I) dependence on ill-specified or implausible principles of p a r s e r operation; (2) d e p e n d e n c e on questionable a s s u m p t i o n s about syntax; (3) lack Of provision, even in principle, for i n t e g r a. | ON PARSING PREFERENCES Lenhart K. Schubert Department of Computing Science University of Alberta Edmonton Abstract. It is argued that syntactic preference principles such as Right Association and Minimal Attachment are unsatisfactory as usually formulated. Among the difficulties are 1 dependence on ill-specified or implausible principles of parser operation 2 dependence on questionable assumptions about syntax 3 lack of provision even in principle for integration with semantic and pragmatic preference principles and 4 apparent counterexamples even when discounting 1 3 . A possible approach to a solution is sketched. 1. Some preference principles The following are some standard kinds of sentences illustrating the role of syntactic preferences. 1 John bought the book which I had selected for Mary 2 John promised to visit frequently 3 The girl in the chair with the spindly legs looks bored 4 John carried the groceries for Mary 5 She wanted the dress on that rack 6 The horse raced past the barn fell 7 The boy got fat melted 1 - 3 illustrate Right Association of pp s and adverbs . the preferred association of these modifiers with the rightmost verb phrase or noun phrase they can modify Kimball 1973 . Some variants of Right Association also characterized as Late Closure or Low Attachment which have been proposed are Final Arguments Ford et al. 1982 and Shifting Preference Shieber 1983 the former is roughly Late Closure restricted to the last obligatory constituent and any following optional constituents of verb phrases while the latter is Late Closure within the context of an LR 1 shift-reduce parser. Regarding 4 it would seem that according to Right Association the PP for Mary should be preferred as postmodifier of groceries rather than carried yet the opposite is the case. Frazier Fodor s 1979 explanation is based on the assumed phrase structure rules VP - V NP pp and NP - NP PP attachment of the pp Into the VP minimizes the resultant number of nodes. This principle