Coherence structure and lexical cohesion in expository and persuasive textsConstraints in Discourse III30 July 1 August 2008

Ildik Berzlnovich, Markus Egg, Gisela RedekerUniversity of GroningenCenter for Language and Cognition

Modelling Textual Organisation (MTO)financed by a grant from NWOproject leaders: Markus EggGisela Redeker

http://www.let.rug.nl/mto/The MTO Project

Lexical cohesion is more closely aligned with coherence in thematically organised texts than in intentionally organised texts.

Specifically:close alignment in expository textsless or no alignment in persuasive textsAlignment hypothesis

Discourse organisationCorpusMethod (genre, coherence, cohesion)Results (coherence, cohesion, alignment)ConclusionFuture work Outline

GENRE 1 GENRE 2 COHERENCE COHERENCE COHESION COHESION text 1 text 1 COHERENCE COHERENCE COHESION COHESION text 2 text 2 Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

GENRE 1 GENRE 2 COHERENCE COHERENCE COHESION COHESION text 1 text 1 COHERENCE COHERENCE COHESION COHESION text 2 text 2 Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

GENRE 1 GENRE 2 COHERENCE COHERENCE COHESION COHESION text 1 text 1 COHERENCE COHERENCE COHESION COHESION text 2 text 2 Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

GENRE 1 GENRE 2 COHERENCE COHERENCE COHESION COHESION text 1 text 1 COHERENCE COHERENCE COHESION COHESION text 2 text 2 Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Genreclass of communicative events with common communicative purposes shared in a discourse community (Swales 1990)global schematic structure moves

Coherenceunderlying relations between propositions in text

Cohesionsemantic relations between surface elements in textDiscourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Corpus in the MTO projectexpository texts- encyclopedia entries- short news storiespersuasive texts- fundraising letters - advertisementsmixed genres- news analyses, commentaries, editorials (?)- reviewsDiscourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Texts for pilot studyexpository texts: encyclopedia entries (EE01, EE02)persuasive texts: fundraising letters (FL01, FL02)

Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Encyclopedia entriesname the objectdefine the objectdescribe in general (e.g., size, age, category)describe details (e.g., surface, past/future development, discovery)

Fundraising letters - seven moves (Upton 2002)get attentionintroduce the cause and/or establish credentials of organisationsolicit responseoffer incentivereference insertexpress gratitudeconclude with pleasantriesDiscourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Fragment from EE01 (De Zon)Na vorming van de zon en het zonnestelsel is onze ster begonnen aan een lang bestaan als zogenaamde dwergster. In de dwergfase van het leven van de zon wordt de energie die ze uitstraalt in het centrum geproduceerd door fusie van waterstof tot helium. De zon is nu ongeveer vijf miljard jaar oud en heeft nog brandstof voor nog eens vijf miljard jaar.

After the forming of the sun and the solar system, our star began its long existence as a so-called dwarf star. In the dwarf phase of its life, the energy that the sun gives off is generated in its core through the fusion of hydrogen into helium. The sun is about five billion years old now and it still has enough fuel for another five billion years.Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Rhetorical Structure Theory (Mann & Thompson 1988)functional relations between propositionsreconstruction of writers purposessubject-matter vs. presentational relationsmononuclear relations multinuclear relations

Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

hierarchy

Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

hierarchyDiscourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

lexical cohesion network of relationslexical semantic relations (Halliday & Matthiessen 2004, Morris & Hirst 1991 )- repetition- systematic semantic relationshyponymy (hyperonymy, co-hyponymy)meronymy (holonymy, co-meronymy)synonymyantonymy- collocationDiscourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Repetition

Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Hyponymy

Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Meronymy

Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Synonymy

Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Collocation

Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Centrality of discourse unitsDiscourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future workin coherence structure

in lexical cohesionEDUs Moves smallest units top level in RST tree of RST tree

lexical cohesive links average lexical per EDU cohesive density

EE01 NAME DEFINE DESCRIBE IN GENERALDESCRIBE DETAILSDiscourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

FL01GETATTENTION GETATTENTION INTRODUCE CAUSECREDENTIALS OF ORGANISATION SOLICIT RESPONSE EXPRESS GRATITUDEDiscourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

Discourse organisation Results (coherence, cohesion, alignment)Corpus ConclusionMethod (genre, coherence, cohesion) Future work

Coherence relationsEE01 EE02FL01FL02Subject-matter (incl. multinuclear) relations28261010Presentational relations 0 11210

Discourse organisation Results (coherence, cohesion, alignment)Corpus ConclusionMethod (genre, coherence, cohesion) Future work

Discourse organisation Results (coherence, cohesion, alignment)Corpus ConclusionMethod (genre, coherence, cohesion) Future work

EE011NAME2-4DEFINE5-16DESCRIBE IN GENERAL17-31DESCRIBE DETAILSDiscourse organisation Results (coherence, cohesion, alignment)Corpus ConclusionMethod (genre, coherence, cohesion) Future work

Chart5

20

315

1619

2818

269

129

85

31

00

170

11

11

01

01

01

01

136

12

53

05

22

84

106

14

30

00

22

20

11

01

10

external links

internal links

Number of external and internal cohesive links

FL01 external vs internal links

EDUs123456789101112131415161718192021222324

external links1210501725292031154105110005

internal links337155041101327421222110

total links151312122761030443128317312115

X5X

XXX

FL01 external vs internal links

external links

internal links

Number of external and internal cohesive links

EE01 external vs internal links

EDUs12345678910111213141516171819202122232425262728293031

external links23162826128301711000013150281013022101

internal links0151918995100111111623524640020110

total21835463521134017221111193854121653042211

EE01 external vs internal links

external links

internal links

Number of external and internal cohesive links

Sheet3

FL011-8GET ATTENTION9-11INTRO-DUCECAUSE12-19ESTABLISHCREDENTIALS OFORGANISATION20-23SOLICIT RESPONSE24EXPRESSGRATITUDEDiscourse organisation Results (coherence, cohesion, alignment)Corpus ConclusionMethod (genre, coherence, cohesion) Future work

Diagramm2

123

103

57

01

175

25

50

24

91

21

00

31

13

12

57

44

12

01

52

12

102

01

01

50

external links

internal links

Number of external and internal cohesive links

FL01 external vs internal links

EDUs123456789101112131415161718192021222324

external links1210501725292031154105110005

internal links337155041101327421222110

total links151312122761030443128317312115

X5X

XXX

FL01 external vs internal links

external links

internal links

Number of external and internal cohesive links

EE01 external vs internal links

EDUs12345678910111213141516171819202122232425262728293031

external links23162826128301711000013150281013022101

internal links0151918995100111111623524640020110

total21835463521134017221111193854121653042211

EE01 external vs internal links

external links

internal links

Number of external and internal cohesive links

Sheet3

EE01Discourse organisation Results (coherence, cohesion, alignment)Corpus ConclusionMethod (genre, coherence, cohesion) Future work

FL01Discourse organisation Results (coherence, cohesion, alignment)Corpus ConclusionMethod (genre, coherence, cohesion) Future work

EE: Define is the central move both in coherence and in lexical cohesionFL: Solicit response is the central move in coherence, but no central move was found for lexical cohesion

alignment much closer for EE than for FLDiscourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work

corpus building- more texts- more genres (e.g., advertisements, reviews)

refinement of centrality measurescomparison of RST trees and tree structures based on lexical cohesion

Discourse organisation ResultsCorpus ConclusionMethod (genre, coherence, cohesion) Future work