What is a unit of communication? Theories of discourse meaning depend in part on a specification of the basic units of a dicouse and the relations that can hold among them. Discourse processing requires an ability to determine to which portions of a discourse an individual utterance relates. Thus the role of discourse structure in discourse processing derives both from its role in cohesion, coherence, RST delimiting units of discourse meaning and... Magdalena Wolska 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 2/33 What is a unit of communication? Sentences cannot be processed in isolation Coreference Segmentation and Ordering M: hi. d4 to d6. J: uh–huh. (week passes) J: a3 to a7. M: hmmm. (2 weeks pass) The pool for members only. Please use the toilet, not the pool. Please use the toilet, not the pool. The pool for members only. M: Queen beats the laufer at e1. Check. ... 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 3/33 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 4/33
“Assume that you have collected an arbitrary set of well-formed “Consider, for example, the difference between passages (18.71) and independently interpretable utterances, for instance, and (18.72). Almost certainly not. The reason is that these utterances, by randomly selecting one sentence from each of the previous when juxtaposed, will not exhibit coherence. Do you have a discourse? chapters of this book. Do you have a discourse? Almost certainly Assume that you have collected an arbitrary set of well-formed not. The reason is that these utterances, when juxtaposed, and independently interpretable utterances, for instance, will not exhibit coherence. Consider, for example, the difference by randomly selecting one sentence from each of the previous between passages (18.71) and (18.72).” chapters of this book.” (JM:695) vs…. 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 5/33 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 6/33 Discourse has structure • Linguistic structure Discourse segments can be connected in a limited number of ways • Rhetorical relations � coherence • Intentional structure There exist linguistic devices that make the structure explicit Discourse comprehension consists of recognizing the structure 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 7/33 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 8/33
– Set of clues – Model: domain-independent rhetorical • Linguistic structure • Linguistic structure • linguistic (discourse markers) structure (RST) • prosodic • non-verbal (e.g. gesture) – Defines binary relations between • Rhetorical relations • Rhetorical relations discourse units – Grammar (analogous to sentence grammar) • Intentional structure – Examples of relations: • Intentional structure Justification, Evidence, Concession, Elaboration, Contrast – Relations may be made explicit by linguistic cues – Discourse tree built compositionally 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 9/33 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 10/33 • Linguistic structure • Linguistic structure [No matter how much one wants to stay a non- – Utterances == actions smoker,] A [the truth is that the pressure to smoke in junior high is greater than it will be any – Intentions of speaker � a plan to other time of one’s life.] B [We know that 3,000 • Rhetorical relations • Rhetorical relations teens start smoking each day,] C [although it is a communicate them fact that 90% of them once thought that smoking was something they’ll never do] D . – Hearer: understand intentions • Intentional structure • Intentional structure (EVIDENCE, C, B) – Model: hierarchical structure of (CONCESSION, C, D) (communicative) goals of speaker (RESTATEMENT, D, A) 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 11/33 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 12/33
Cohesion • Linguistic structure – Abstract model of discourse is a tripartite structure comprising: � discourse and dialog exhibit patterns of lexical connectivity • Rhetorical relations linguistic structure (utterances) cohesive devices: intentiona l structure (intentions) • Intentional structure – Reference – Lexical repetition dynamically-changing attentional – Use of synonymy – Time flies. structure (model of objects, properties, and – Ellipsis – You can’t; they fly too quickly. relations between them that are salient at (Halliday and Hasan 1982) – Conjunctions every point) 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 13/33 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 14/33 Coherence vs. Cohesion Coherence vs. Cohesion – Coherence: structural, functional relations between sentences – Coherence: structural, functional relations between sentences – Cohesion: non-structural, text-forming relations that “tie” parts of – Cohesion: non-structural, text-forming relations that “tie” parts of discourse together discourse together John went to his favourite music John went to his favourite music When Teddy Kennedy paid a courtesy call on Ronald store to buy a piano. store to buy a piano. Reagan recently, he made only one Cabinet suggestion. Western surveillance satellites confirmed huge Soviet troop He had frequented the store for It was a store John had concentrations virtually encircling Poland. frequented for many years. many years. (Hobbs 1982) E: Forks have windows. He was excited that he could He was excited that he could P: Yes they do. Augmented pretension. Four plus four equals finally buy a piano. finally buy a piano. sixteen. It is a larger element, it’s photographic and phototrophic, but it is a higher number, higher course-work. It grows through It was closing just as John He arrived just as the store was evaporation or nocturnalism, it is sleepy, you rediscover it closing for the day. arrived. and I suppose forks could have windows through evaporation. 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 15/33 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 16/33
Coherent, cohesive discourse: Anaphora: pronominal anaphoric reference • individual, temporal, spatial, „abstract entity” – My neighbor has a monster Harley 1200. They are huge but gas- efficient bikes. discourse markers/cue phrases – One should mind their own business. conventional conversational sequences – We had two hurricanes hit us in the teeth, one of which you can read about in the current New Yorker if you find the place. It’s called “Our Windswept Correspondents” and I am they . 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 17/33 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 18/33 Anaphora: nominal (definite NP) Anaphora: surface-count and demonstrative – Al bought a car the other day. […] He took it out of the garage last – Sarah could leave but she was also given an option to stay; she night with the help of George Cottrell, and the thing gave forth such chose the latter . immense clouds of smoke that one man came running up and asked – Have just driven to town, carrying our cook 1 and our cook’s dog 2 . me where the fire was. Gave the one 1 $300 in currency and placed the other 2 in the infirmary, – […] I wanted a Trumpeter Swan who could play like Louis Armstrong, with eczema. and I simply created him and named him Louis. The cutting of the webs between his toes is also fantastical, just as the bird itself is; […]. 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 19/33 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 20/33
Strained anaphora Temporal anaphora – John became a guitarist because he thought that it was a beautiful – If I must declare today that I am not a Communist, tomorrow I shall instrument. have to testify that I am not a Unitarian. And the day after , that I never belonged to a dahlia club. 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 21/33 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 22/33 Spatial anaphora Abstract entity anaphora Each Fall, penguins migrate to Fiji. – The awful hot spell broke last night and today is clear and beautiful, […] Across the street , the entire janitorial family has blossomed out That ’s where they wait out the winter. in pink carnations, […] That ’s when it’s cold even for them. That ’s why I’m going there next month. It happens just before the eggs hutch. (Webber 1988) Send engine to Elmira. That’s six hours. (Byron 2002) 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 23/33 10 czerwca 2005 SS 2005 – PTT – conhesion,coherence, RST 24/33
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