tailieunhanh - Báo cáo khoa học: "Natural Language Front-Ends to Databases: Design and the Customisation Bottleneck"

NLFE to databases have failed in a commercial context, largely because of two reasons. Current approaches to the management of ambiguity by relying on inference over a world model create ungoing customisation requirements. Furthermore the design of NLFEs is subject to constraints which research in CL/ NLP does not address. In particular, standard parsing techniques (including "robust" ones) require complete lexica and cannot be deployed because new data would create a constant need for dictionary update. The SQUIRREL [1] system (SERC Grant GR/E/ 69485) addresses some of these problems: its design reduces customisation effort as words are interpreted without. | Natural Language Front-Ends to Databases Design and the Customisation Bottleneck Anne De Roeck University of Essex Department of Computer Science Wivenhoe Park Colchester CO4 3SQ e-mail deroe@ 1. SQUIRREL Motivation and Design. NLFE to databases have failed in a commercial context largely because of two reasons. Current approaches to the management of ambiguity by relying on inference over a world model create ungoing customisation requữements. Furthermore the design of NLFEs is subject to constraints which research in CL NLP does not address. In particular standard parsing techniques including robust ones require complete lexica and cannot be deployed because new data would create a constant need for dictionary update. The SQUIRREL 1 system SERC Grant GR E 69485 addresses some of these problems its design reduces customisation effort as words are interpreted without reference to world models. The lexicon is assumed to be incomplete unknown words are given interpretations by exploiting typing information contained in die datamodel. In addition SQUIRREL demonstrates that NLFEs can allow for inteưogation of integrity constraints usually invisible to users. It is important to note that no new aspects of standard database management systems are involved SQUIRREL intends to explore to what extent the state of the art in NLP CL and Formal Semantics can be exploited in the design of NLFE to relational databases under constraints imposed by good sofware engineering protocol. It aims to develop a modular portable design to plug in to public domain database technology requiring minimal customisation. SQUIRREL consists of a series of mappings translating NL expressions into SQL. Its highly modular design allows parts of the system to be ported without affecting other parts. Expressions in English are assigned syntactic and semantic representations on the basis of a lexicon and a context-free feature based grammar. The lexicon is incomplete unknown words are .