Christel Kemke 2007/08 COMP 4060 Natural Language Processing Discourse and Dialogue

Christel Kemke

COMP 4060 Natural Language Processing

Discourse and Dialogue

2007/08 Christel Kemke

Discourse and Dialogue

Discourse Phenomena Speech Acts Dialogue Acts


Discourse

Discourse = collocated, related group of sentences

Monologues and Dialogues Referring Expressions: he, she Coherence Discourse Structure

see Jurafsky and Martin, Ch. 18 and 19


Reference

Referring Expressions Referent

the Jurafsky

the 406 textbook


Reference

Discourse Model - keeps track of representations of entities mentioned in discourse so far

Referring Expression - encodes information / signals for hearer to identify referent

Methods: Determine mapping from sign in referring expression to set

of beliefs / discourse model of hearer. Referents can be different parts, aspects of a sentence or

utterance. Use constraints on co-reference (syntax, discourse) to

determine mapping.


Reference

"According to John, Bob bought Sue an Integra, and Sue bought Fred a Legend."

a) But that turned out to be a lie. speech actb) But that was false. propositionc) That caused Sue to become rather poor. eventd) That caused both of them to become rather

poor. combination of events


Reference

Indefinite / definite noun phrases specific / non-specific entity

Pronouns salience (last mentioned) cataphora (pronoun mentioned before entity) bound in context of "quantified variable"

Demonstratives (this, that) "spatial proximity" (metaphorically), e.g. old - new

car


Coherence

Coherence Relations (Hobbs) – model "connectedness" of sentences in text

ResultJohn bought an Acura. His father went ballistic.

ExplanationJohn hid Bill's car keys. He was drunk.

ParallelJohn bought an Acura. Bill leased a BMW.

ElaborationJohn bought an Acura this weekend. He purchased a new beautiful Acura for ... on Saturday afternoon.

OccasionJohn bought an Acura. He drove to the ballgame.


Discourse Structure

Arrangement of sentence elements into (coherent) text / analysis of text according to coherence relations

Jurafsky and Martin, Figure 18.10, p. 705

Christel Kemke

Speech Acts


Three Aspects of Speech Acts

Locutionary: the literal meaning of the utterance

Illocutionary: the social function that the utterance or written text has (e.g. informing, ordering, warning, undertaking.)

Perlocutionary: the result or effect that is produced by the utterance in that given context (e.g. convincing, persuading, deterring.)


Illocutionary Acts

Assertives Directives Commissives Permissives Prohibitives Declaratives


Speech Acts

Assertives committing the speaker to something's being the case “The door is shut.”

Directives attempts by the speaker to get the addressee to do something “Shut the door.”

Commissives committing the speaker to some future course of action “I will shut the door.”

Expressives expressing the psychological state of the speaker about a state

of affairs "Thanks for shutting the door."


Speech Acts

Permissives allow / permit the hearer to a course of action as

described by the propositional content of the utterance "You may shut the door."

Prohibitives deny the hearer to a course of action as described by the

propositional content "Don't shut the door."

Declarations / Declaratives bringing about a different state of the world via the

utterance "You're fired."


DAMSL - Dialogue Act Markup in Several Layers

Statement Info-request

Check Influence on Addressee Influence on Speaker

Offer Commit

Conventional Opening ...


Questions and Frames


Reference

Dan Jurafsky and James H. Martin, Speech and Language Processing, 1st Edition, Chapters 18 and 19, Prentice-Hall, 2000

Documents

Christel Kemke 2007/08 COMP 4060 Natural Language Processing Discourse and Dialogue