Week 10: coherence Flashcards
Sentences are locally coherent when…
…they are all connected.
What is relational coherence?
When every proposition that is introduced is rhetorically connected to another piece of information in the discourse.
Resulting in a single connected structure for the whole discourse.
All anaphoric expressions can be resolved.
What is entity coherence?
Discourse is coherent to the extent that it is consistent in the entities that it focuses on.
Complementary to discourse coherence.
Lexical coherence
Views text as coherent when there are clear relations between the words used in nearby sentences.
The required relations can be discrete (formal relations such as hyponymy) or graded (e.g. distributional similarity).
Rhetorical Structure Theory
A type of relational coherence
An approach that analyses discourse into a hierarchical structure of relations between discourse segments.
In Rhetorical Structure Theory, what are relations defined between?
An independently interpretable NUCLEUS and a dependent SATELLITE.
(Some relations have multiple nuclei)
What is the first step in RST analysis?
Identifying the elementary discourse units.
What are the elementary discourse units?
Non-overlapping subsequences between which relations hold.
Segmented Discourse Representation Theory
A type of relational coherence.
Integrates rhetorical relations with compositional formal semantics.
A hearer’s goal is to find a coherent model of discourse - one in which all elements combine to form a single whole.
What type of coherence does Centring Theory use?
Entity based coherence
What is the backwards looking centre (C_b)?
The salient entity at U_n, this must have been mentioned in the immediately preceding utterance.
What are the forward looking centres (C_f)?
The potential future salient entries.
These are ranked for likelihood of being the salient entity in next utterances.
What is the preferred centre (C_p)?
The top-ranked entity.
What is rule 1 of centring theory?
If any element C_f(U_n) is realised as a pronoun in utterance U_(n+1), then C_b(U_(n+1)) must be realised as a pronoun too.
What is rule 2 of centring theory?
Transition states are ordered. Continue is preferred to retain, retain is preferred to smooth-shift, smooth-shift is preferred to rough-shift.
