G22.2590 - Natural Language Processing - Spring 2006 Prof. Grishman

Lecture 11 Outline

April 11, 2006

Assignment #9 ... discuss conditional probabilities

Syntax-Driven Semantic Analysis  (J&M Chapter 15))

Complete oour discussion of semantic representations (Lecture 10 notes)

Review examples of logical forms

<>Discuss rules for producing semantic representations of sentences using syntax-driven semantic analysis

Scoping resolution:  converting quasi-logical form to logical form (with conventional quantifier scope)

Factors in resolving scope:

Strategies for data base query applications

Assuming queries are full grammatical sentences: (we will consider how to handle fragmentary queries as part of discourse processing)

A Canonical Representation?  (Lexical Semantics - J&M 16.1 - 16.2)

Logical form brings us a step closer to a 'canonical representation', where there is one representation for a meaning (and one meaning for a representation).  For example, active and passive forms will translate to the same logical form.

The predicates in our logical form are words, which is not satisfactory:
But this far from exhausts the range of paraphrases (different ways of conveying the same meaning).  Building larger inventories of paraphrases remains a very difficult problem for NLP.