wg2 pwi24617-5 semaf - discourse structure
DESCRIPTION
WG2 PWI24617-5 SemAF - Discourse Structure. 20101014, Berlin HASIDA Koiti [email protected] AIST, Japan. Introduction (Concerns). annotation, production, translation, etc. of documents discourse structures not only in linguistic content but also in (possibly silent) video, etc. - PowerPoint PPT PresentationTRANSCRIPT
Introduction (Concerns) annotation, production, translation, etc. of
documents discourse structures not only in linguistic content but
also in (possibly silent) video, etc. documents without predefined total temporal
ordering of presentation, such as hypertexts and games
organization of discourse structures consisting of eventualities (or what represent them, such as sentences, clauses, phrases, video scenes, and so on) and discourse relations among them
to minimize the set of discourse relations by attributing presentational information to other parts of discourse structures
If the discourse structures of speech and other linguistic data contained in motion pictures were fitted to this scheme, then multilingual subtitles to these pictures could be composed for a reduced cost by means of some standardized tool for multilingual translation.
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Scope
To describe how discourse constituents (eventualities) are combined through (possibly implicit) discourse connectives (discourse relations) to constitute a discourse (its semantic content).
Elaboration, etc.Criteria for including certain relations
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typically sentencestypically sentences
factual and inferentialfactual and inferential
PoliciesMinimize the set of discourse
relations while addressing semantic differences.Concentrate on semantic content
representation, minimizing presentational aspects (such as importance: nucleus/satellite distinction) and maximizing the versatility of the representation.
Maximally accommodate polymorphism.
Use discourse trees to encode presentational aspects.
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TermsEvent???: event (possibly dialogue act) or
state or process or their abstraction (type)
discourse relation: semantic relation among eventualities
discourse graph: graph representing discourse semantics in which nodes represent eventualities and links among them represent discourse relations
discourse tree (discourse annotation?): annotated tree structure of linearly-ordered discourse representing presentational structures of the discourse besides its semantic content
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Discourse Relationrelations among eventualities and/or
their types[I worked hard {to pass the exam}].
factual and/or inferential.[[Tom came] {because [Mary came]}].
= [[I guess Tom came] {because [Mary came]}].
purposepurpose event type($2)
event type($2)
event($1)
event($1)
-inference-inference reasonreasonconclusionconclusion
-causes-causes causecauseresultresult
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authoring of content must be easyauthoring of content must be easy
semantic annotation is necessarysemantic annotation is necessary
inferenceinference
inferenceinference
huge amount of content is necessaryhuge amount of content is necessary
retrieval must be quick and easyretrieval must be quick and easy
realize ubiquitous information servicerealize ubiquitous information service
purposepurpose
purposepurpose
inferenceinference
Discourse Graph
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In previous annotation practices, discourse relation may concern not the whole apparent argument but its core wrapped in an attitude report, a modal operator, etc.
Wrapped Arguments/Metonymy
Remember all those vegetablesyou slipped under the table ?Remember all those vegetablesyou slipped under the table ?
Maybe that’s whySparky lived so long.Maybe that’s whySparky lived so long.
you slipped under the tableyou slipped under the table
Sparky lived so longSparky lived so long
causescauses
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you slipped those vegetable under the tableyou slipped those vegetable under the table
Discourse Graph is Explicit
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remember?remember?
maybemaybe
Sparky lived so longSparky lived so long
causescauses
contentcontent
objectobject
A minus sign is the inverse operator.A minus sign is the inverse operator.
Discourse Tree
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[ [Semantic annotation is necessary {-inference because {conjunction [2 retrieval must be quick and easy]
and [3 authoring of content must be easy]}}].
[2 Retrieval must be quick and easy
{purpose in order to [0 realize ubiquitous information access]}].
[3 Authoring of content must be easy
{-inference because [1 huge amount of content is necessary
{purpose in order to [0 realize ubiquitous information access]}]}].
]
discourse connectivediscourse connective
discourse relationdiscourse relation
The arg. of a discourse
connective is the 2nd arg. of the
discourse relation.
The arg. of a discourse
connective is the 2nd arg. of the
discourse relation.
A discourse connective depends on the 1st arg. of the
discourse relation.
A discourse connective depends on the 1st arg. of the
discourse relation.
A pair of curly brackets is a
discourse constituent headed
by a discourse connective.
A pair of curly brackets is a
discourse constituent headed
by a discourse connective.
Discourse Tree (cont.)
Encodes presentational aspects including importance (nucleus/satellite distinction) possibly partially.
The current syntax is not a serious proposal.It should be easy to come up with a LAF-
based representation of DTs.Do we have to standardize it?
Harmonization requirements?with SynAF and other annotation practices
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ImportanceAbstract importance (nucleus/satellite
distinction) away from discourse relation, as it’s a matter of presentation.[1 {Although its rooms are small}, the hotel
is large]. [{So1} Tom will stay there].
[2 {Although the hotel is large}, its rooms are small]. [{So2} Mary won’t stay there].
the hotel is largethe hotel is large
its rooms are smallits rooms are small
conflictconflict
Tom will stay thereTom will stay there
Mary won’t stay thereMary won’t stay there
inferenceinference
inferenceinference
symmetricsymmetric
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Importance (cont.)
Unification between inverse relations:means vs. purposecause vs. resultreason vs. conclusionattribution vs. contentgeneral vs. specificwhole vs. part
Any criterion under which to choose names and directions of these relations?
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Polymorphism, Metonymy, and Projection
Object/Eventualitysimilardissimilargeneral-specificset-memberwhole-partexamplerestatementcomparisonattribution-contentmeans-purposecomment-topic
Temporal Projectioncircumstancebefore-afteruntilsimultaneous
Instance/Typepurposeconditionalunconditional
Semantics/Pragmaticsenablement
dom
ain
=ra
ng
e
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Object/Eventuality
Some relations concern not only eventualities but also objects.comparison
[Tom is taller {than Mary is tall}].attribution-content
[I believe {that he’s right}].[the belief {that he’s right}]
means-purpose[cut it {with this sword}][cut it {by using this sword}]
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Instance/Type
Some relations may concern both instances and types of eventualities.purpose
[I used this sword {to cut it}].conditional
[{If you’re going to school}, it’s eight o’clock].
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Semantics/Pragmaticsenablement
[1Here’s coffee.] [{So1} drink it].
The fact that here’s coffee enables the precondition for the imperative.
[{Since here’s coffee}, it’s possible that you drink it].
enablesenableshere’s coffeehere’s coffee Drink it.Drink it.
dialog actdialog act
enablesenableshere’s coffeehere’s coffee you drink ityou drink it
sem. contentsem. content
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Temporal Projection
[Tom came {at 8 o’clock}].[Tom came {when Mary came}].
time(semantic
role)
time(semantic
role)
circumstance(discourse
rel.)
circumstance(discourse
rel.)
equality orProjection?equality orProjection?equality orprojection?equality orprojection?
`time’ and `circumstance’ may be unified.
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Taxonomy
Ted Sanders’ 3 (out of 4) dimensionsadditive vs. causalpositive vs. negativefactual vs. inferential
Cf. the other dimension concerns linear orderbasic vs. non-basic
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additivepositive
Elaboration: specific, part, step, object, member, example, extraction, minimum, detail, restatement, definition
Attribution: contentBackground: background, circumstanceComparison: similarity, proportionComplement: supplementAdditive: coordination, additionManner: manner
negativeContrast: contrast, dissimilarity, disjunction, substitutionComplement: constraintComparison: comparison, preference
causalpositive
Causality: causes, motivates, triggersEnablement: purpose, enablesInference: inference, explanationEvaluation: evaluation, interpretation, commentCondition: conditional
negativeConcession: conflictCondition: otherwise, unconditional, compromise 20