MPhil Thesis Defence


"Interpreting Tables in Text using Probabilistic Two-Dimensional
Context-Free Grammars"

By

Mr. Wing Kuen Lee


Abstract

Table interpretation is the process of extracting meaningful information
from textual tables.  More precisely, interpreting tables entails
producing a semantic analysis in the form of a logical representation that
is suitable for the kinds of inferences one would need to perform upon the
information contained in the table.  To a large extent, the quality of a
table interpretation model depends on how accurately the model
disambiguates the types of the table and its subparts.  This in turn
depends on three major factors that we address in this thesis: (1) the
expressiveness and suitability of the logical representation for semantic
interpretation, (2) the adequacy of the inventory of table types and
subparts, and (3) the power of the disambiguation algorithms.  We present
a new elegant and extensible table analysis model that is capable of
interpreting an unusually wide range of textual tables in documents.
Unlike the few existing table analysis models, which largely rely on
relatively ad hoc heuristics, our linguistically-oriented approach is
systematic and grammar based, which allows our analysis model to be
concise and yet recognize a wider range of types of tables than others.
Specifically, our table analysis model introduces the use of Viterbi
parsing under probabilistic two-dimensional CFGs.  This cleaner
grammatical approach facilitates not only greater coverage, but also
grammar extension and maintenance, as well as a more direct and
declarative link to semantic interpretation, for which we also introduce a
cleaner underlying logical model that exploits database theory.  In
disambiguation experiments on finding appropriate semantic interpretations
of unseen web tables from different domains, our model obtained 65%
precision and 74% recall.


Date:				Friday, 26 August 2005

Time:				2:00p.m.-4:00p.m.

Venue:				Room 2465
				Lifts 25-26

Committee Members:		Dr. Dekai Wu (Supervisor)
				Prof. Derick Wood (Chairperson)
                        	Dr. Dit Yan Yeung
				Dr. Pascale Fung (ELEC)


**** ALL are Welcome ****