G22.2590 - Natural Language Processing - Spring 2010 Prof. Grishman

Lecture 10 Outline

April 1, 2010

Term projects:  importance of evaluation.  Separating development and test data.  Collecting data for interactive tasks ("Wizard of Oz" methods).

Discourse.  Until now we considered the structure and meaning of sentences in isolation.  We now turn to issues primarily connected with multi-sentence text -- discourse.

Reference Resolution (J&M 21.3-8)


Types of referring expressions


Resolving pronoun reference

Resolving other referring expressions

Anaphora resolution in Jet

Using anaphora resolution for extraction:  an example

In many cases, we want to be able to retrieve an argument from context when it is not part of the immediate syntactic structure.  A simple way of doing this is to generate a zero anaphor (an ngroup constituent not spanning any text) and then let reference resolution map it to an entity.  We have created a version of the AppointPatterns which uses this method to collect organization names and, in some cases, people names.

Text Coherence and Coreference

Why are we interested in analyzing the structure of a discourse beyond the sentence level? How to analyze and utilize text coherence?