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Selecting tense, aspect, and connecting words in language generation
Generating language that reflects the temporal organization of represented knowledge requires a language generation model that integrates contemporary theories of tense and aspect, temporal representations, and methods to plan text. This paper presents a model that produces complex sentences that reflect temporal relations present in underlying temporal concepts. The main result of this work is the successful application of constrained linguistic theories of tense and aspect to a generator which produces meaningful event combinations and selects appropriate connecting words that relate them
A Principled Framework for Constructing Natural Language Interfaces To Temporal Databases
Most existing natural language interfaces to databases (NLIDBs) were designed
to be used with ``snapshot'' database systems, that provide very limited
facilities for manipulating time-dependent data. Consequently, most NLIDBs also
provide very limited support for the notion of time. The database community is
becoming increasingly interested in _temporal_ database systems. These are
intended to store and manipulate in a principled manner information not only
about the present, but also about the past and future.
This thesis develops a principled framework for constructing English NLIDBs
for _temporal_ databases (NLITDBs), drawing on research in tense and aspect
theories, temporal logics, and temporal databases. I first explore temporal
linguistic phenomena that are likely to appear in English questions to NLITDBs.
Drawing on existing linguistic theories of time, I formulate an account for a
large number of these phenomena that is simple enough to be embodied in
practical NLITDBs. Exploiting ideas from temporal logics, I then define a
temporal meaning representation language, TOP, and I show how the HPSG grammar
theory can be modified to incorporate the tense and aspect account of this
thesis, and to map a wide range of English questions involving time to
appropriate TOP expressions. Finally, I present and prove the correctness of a
method to translate from TOP to TSQL2, TSQL2 being a temporal extension of the
SQL-92 database language. This way, I establish a sound route from English
questions involving time to a general-purpose temporal database language, that
can act as a principled framework for building NLITDBs. To demonstrate that
this framework is workable, I employ it to develop a prototype NLITDB,
implemented using ALE and Prolog.Comment: PhD thesis; 405 pages; LaTeX2e, uses the packages/macros: amstex,
xspace, avm, examples, dvips, varioref, makeidx, epic, eepic, ecltree;
postscript figures include