tailieunhanh - Báo cáo khoa học: "Don’t ‘have a clue’? Unsupervised co-learning of downward-entailing operators"

Researchers in textual entailment have begun to consider inferences involving downward-entailing operators, an interesting and important class of lexical items that change the way inferences are made. Recent work proposed a method for learning English downward-entailing operators that requires access to a high-quality collection of negative polarity items (NPIs). | Don t have a clue Unsupervised co-learning of downward-entailing operators Cristian Danescu-Niculescu-Mizil and Lillian Lee Department of Computer Science Cornell University cristian@ llee@ Abstract Researchers in textual entailment have begun to consider inferences involving downward-entailing operators an interesting and important class of lexical items that change the way inferences are made. Recent work proposed a method for learning English downward-entailing operators that requires access to a high-quality collection of negative polarity items NPIs . However English is one of the very few languages for which such a list exists. We propose the first approach that can be applied to the many languages for which there is no pre-existing high-precision database of NPIs. As a case study we apply our method to Romanian and show that our method yields good results. Also we perform a cross-linguistic analysis that suggests interesting connections to some findings in linguistic typology. 1 Introduction Cristi Nicio . is that adjective you ve mentioned. Anca A negative pronominal adjective. Cristi You mean there are people who analyze that kind of thing Anca The Romanian Academy. Cristi They re crazy. From the movie Police adjective Downward-entailing operators are an interesting and varied class of lexical items that change the default way of dealing with certain types of inferences. They thus play an important role in understanding natural language 6 18-20 etc. . We explain what downward entailing means by first demonstrating the default behavior which is upward entailing. The word observed is an example upward-entailing operator the statement i Witnesses observed opium use. implies ii Witnesses observed narcotic use. but not vice versa we write i ii . That is the truth value is preserved if we replace the argument of an upward-entailing operator by a superset a more general version in our case the set opium use was replaced by the superset