Imperfect Querying through Womb Grammars plus Ontologies

Verónica Dahl, Sergio Tessaris, Thom W. Frühwirth

Abstract: Womb grammars, or WGs, are a failure-driven constraintbased parsing mechanism specifically developed for crosslanguage grammar engineering, whose main parsing operation consists of looking for failed constraints between pairs of daughters of a phrasal category. For instance, rather than rejecting those noun phrases where an adjective daughter precedes the noun daughter (a natural mistake for say, an Italian querying in English), a WG checks whether that English ordering requirement fails, and produces a failure indicator if so. Thus, rather than acting solely as filters impeding incorrect sentences from being parsed, the constraints described for a WG can be relaxed to admit mistakes that are personalized to a certain type of user. Syntactic constraints have been the most studied for WGs, since their first aim was to “repair” a known language’s grammar until it reflected that of another language, by modifying constraints that failed with respect to input in the other language. However any other kind of information can also be consulted. In this article we extend WG parsing to incorporate semantic information in view of imperfect querying, and we show how the approach lends itself in particular to ontology-driven enhancements. We assume familiarity with Prolog and in particular, CHR.