Time: Wednesday, November 25, 2009 1:00 p.m
Place: TASC 1 9204 West
**Title: EXTENDING CENTERING THEORY FOR THE MEASURE OF ENTITY COHERENCE **
Centering Theory determines the coherence of a text by identifying the most salient entities in adjacent utterances and observing how they change in salience. This thesis extends Centering Theory by tracking all the entities of the utterance in order to improve the measure of a text’s coherence. Accounting for all entities allows the utterance window to be expanded beyond adjacent utterances, which eliminates the difficulties and compromises associated with choosing either a sentence or a clause as the unit of analysis. Experiments show that tracking all entities instead of a single entity improves the evaluation of text coherence compared to traditional measures of coherence. The model proposed is motivated by linguistic principles and does not require training, alleviating the need for costly training data. The entity coherence model was evaluated on two tasks: sentence ordering and summarization. The sentence ordering experiment involved identifying the original text amongst a collection of its permutations.