Discourse Resolution Flashcards
Discourse Relation
Implicit relationship between two sentences. This may be ambiguous e.g. is it a narration or an explanation.
Factors influencing discourse interpretation
Cue phrases
Punctuation/intonation and text structure.
Real world content.
Tense and aspect.
Summarisation
Can remove explanatory phrases in discourse relation and leave coherent structure still.
Referent
A real world entity that some piece of text refers to.
Referring Expressions
Bits of language used to perform reference by a speaker.
Antecedent
The text initially evoking a referent.
Anaphora
The phenomenon of referring to an antecedent.
Cataphora
Pronoun appearing before their referents are introduced by a proper name or definite description.
Pronoun Agreement
Pronouns generally have to agree in number and gender with their antecedents.
Reflexives
Relexive pronouns must be co-referential with a preceding argument of the same verb while non-reflexive pronouns cannot be.
Pleonastic pronouns
Semantically empty and don’t refer.
Recency
More recent antecedents are preferred. Only relative recently referred to entities are accessible.
Grammatical role
Subjects > objects > everything else
Repeated Mention
Entities that have been more frequently mentioned are preferred.
Parallelism
Entities sharing the same role as the pronoun in the same sort of sentence are preferred.
Coherence effects
The pronoun resolution may depend on the rhetorical/discourse relation that is inferred.
Anaphora resolution algorithms
Formulate pronoun resolution as a classification problem. For each pairing of a pronoun and a candidate antecedent, the classifier has to make a binary decision as to whether the candidate is an actual antecedent, based on the pairing’s features. These are trained and classified using a feature vector.
Pronoun resolution evaluation
Possibility:
Require every pronoun is linked an antecedent and just measure accuracy of links found compared to test data.
Problems: pleonastic pronouns and identification of target NPs due to embedded NPs being a particular issue.
