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Báo cáo khoa học: "A PREFERENCE MECHANISM BASED ON MULTIPLE CRITERIA RESOLUTION"

This paper presents an experimental preference tool des!gned, implemented and tested m the Eurotra pro)ect. The mechanism is based on preference rules which can either compare subtrees pairwise or single out a subtree on the basis of some specified constraints. Scoring permits combining the effects of various preference rules. | A PREFERENCE MECHANISM BASED ON MULTIPLE CRITERIA RESOLUTION Yannis Dologlou Eurotra-GR Margari 22 11525 Athens Greece. Giovanni Malnati Eurofra-IT Gruppo Dima Corso F.Turau 11 C 10128 Torino Italy. Patrizia Paggio patrizia@ eurotra.uucp Eurotra-DK University of Copenhagen Njalsgade80 2300 Kbh S Denmark. ABSTRACT This paper presents an experimental preference tool designed implemented and tested in the Eurotra project. The mechanism is based on preference rules which can either compare subtrees pairwise or single out a subtree on the basis of some specified constraints. Scoring permits combining tne effects of various preference rules. THE PROBLEM The aim of a translation system is to produce the correct translation of a given text. In Eurotra where translation is split up into a series of mappings among intermediate levels of representation provisional overgeneration is a necessary evil Raw et al. 1989 the closer to surface structure a level of representation is the harder it becomes for the parser to produce an unambiguous result In the Eurotra framework the E-framework Bech et al. 1989 overgeneration can be partially controlled by filters which describe parse frees that are to be discarded as not obeying some specified constraints. Thus filters apply to individual objects and are meant to delete inherently wrong representations. But there are cases where the grammar produces multiple analyses of a given input because the input is ambiguous with respect to a given level. All of these analyses are in some sense correct although further processing might discard some of them. Our aim was to design a preference mechanism able to choose the best among a set of acceptable candidates. OUR VIEW OF PREFERENCE Preference has been defined in a number of ways e.g. as a gradual fulfilment of semantic constraints Fass and Wilks 1983 as a lexically induced syntactic bias Ford et al. 1982 as a parsing strategy inde-Ĩ endent of linguistic criteria Frazier and Fodor 978 Pereira .