discourse and dialogue
DESCRIPTION
discourse and dialogue. What is a unit of communication?. M: hi. d4 to d6. J: uh–huh. (week passes) J: a3 to a7. M: hmmm. (2 weeks pass) M: Queen beats the laufer at e1. Check. - PowerPoint PPT PresentationTRANSCRIPT
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discourse and dialogue
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What is a unit of communication?
M: hi. d4 to d6.J: uh–huh.(week passes)
J: a3 to a7.M: hmmm.(2 weeks pass)
M: Queen beats the laufer at e1. Check....
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 delimiting units of discourse meaning and...
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What is a discourse?
“Assume that you have collected an arbitrary set of well-formed
and independently interpretable utterances, for instance,
by randomly selecting one sentence from each of the previous
chapters of this book. Do you have a discourse? Almost certainly
not. The reason is that these utterances, when juxtaposed,
will not exhibit coherence. Consider, for example, the difference
between passages (18.71) and (18.72).”(Jurafsky and Martin:695)
“Consider, for example, the difference between passages
(18.71) and (18.72). Assume that you have collected an arbitrary
set of well-formed and independently interpretable utterances, for
instance, by randomly selecting one sentence from each of the
previous chapters of this book. Almost certainly not. Do you have
a discourse? The reason is that these utterances, when
juxtaposed, will not exhibit coherence.”
vs….
“Assume that you have collected an arbitrary set of well-formed
and independently interpretable utterances, for instance,
by randomly selecting one sentence from each of the previous
chapters of this book. Do you have a discourse? Almost certainly
not ~. The reason is that these utterances, when juxtaposed,
will not exhibit coherence. Consider, for example, the difference
between passages (18.71) and (18.72).”(Jurafsky and Martin:695)
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What is a discourse?
The pool for members only. Please use the toilet, not the pool.The pool for members only.Please use the toilet, not the pool.
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What is a discourse?
sentences are (typically) not processed in isolation
discourse, unlike an arbitratry collection of utterances, forms an intentionally meaningful whole (discourses are „about” something)
discourse has structure
segmentation and orderingcoherencecohesion
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Discourse is internally linked; it „hangs together”
patterns of lexical connectivity cohesion
linguistic text-forming devices:
lexical repetition, synonymy/antonymy, ellipsis/pro-forms, enumeration, parallelism, co-reference (anaphora)
– Time flies.– You can’t; they fly too quickly.(Halliday and Hasan 1982)
– Time flies.– You can’t ~; they fly too quickly.(Halliday and Hasan 1982)
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Anaphora: pronominal
My neighbor has a monster Harley 1200. They are huge but gas-efficient bikes.
One should mind their own business.
Anaphora: nominal (definite NP)
Al bought a car the other day. […] He took it out of the garage last night with the help of George Cottrell, and the thing gave forth such immense clouds of smoke that one man came running up and asked me where the fire was.
[…] I wanted a Trumpeter Swan who could play like Louis Armstrong, 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; […].
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Anaphora: surface-count and demonstrative
Sarah could leave but she was also given an option to stay; she chose the latter.
Have just driven to town, carrying our cook1 and our cook’s dog2. Gave the one1
$300 in currency and placed the other2 in the infirmary, with eczema.
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Temporal anaphora
If I must declare today that I am not a Communist, tomorrow I shall have to testify that I am not a Unitarian. And the day after, that I never belonged to a dahlia club.
Spatial anaphora
The awful hot spell broke last night and today is clear and beautiful, […] Across the street, the entire janitorial family has blossomed out in pink carnations, […]
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Strained anaphora (bridging)
John became a guitarist because he thought that it was a beautiful instrument.
The house was beautiful. The door was painted white and the windows
had blue shutters.
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Abstract entity anaphora
Each Fall, penguins migrate to Fiji.
That’s where they wait out the winter.
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 an engine to Elmira.
That’s six hours.(Byron 2002)
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Ellipsis
The well water had chemicals in it and nothing in the house worked as it should [work].
[I] Have been uncommunicative lately, and [I have been] lagging in life’s race.
I’m afraid my poem isn’t as nicely written as “Paradise Lost,” but anyway, it’s shorter [than “Paradise Lost”] .
Ultimately, even after Garcia was gone, Ruelas was able to cope and move on with his career. And indeed, he has [coped and moved on with his career].
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To form the intended „whole” discourse segments can beconnected in a limited number of ways coherence
there exist linguistic devices that make structure explicit
identity (sameness): that is, that is to say, in other words, ...
opposition (contrast): but, yet, however, nevertheless, whereas, in contrast...
addition (continuation): and, too, also, furthermore, moreover, in addition,...
cause and effect: therefore, so, consequently, thus, it follows that, ...
concession (willingness to consider the other side): admittedly, true, I grant,...
exemplification (shift from general/abstract to specific/concrete idea): for example, for instance, after all, an illustration of, indeed, in fact, specifically,...
discourse comprehension consists of recognizing the structure
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Coherence vs. Cohesioncoherence: structural, functional relations between sentences
cohesion: non-structural, text-forming relations that “tie” parts of discourse together
John went to his favourite music store to buy a piano.
He was excited that he could finally buy a piano.
John went to his favourite music store to buy a piano.
He was excited that he could finally buy a piano.
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John went to his favourite music store to buy a piano.
He was excited that he could finally buy a piano.
John went to his favourite music store to buy a piano.
He was excited that he could finally buy a piano.
Coherence vs. Cohesioncoherence: structural, functional relations between sentences
cohesion: non-structural, text-forming relations that “tie” parts of discourse together
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John went to his favourite music store to buy a piano.
He had frequented the store for many years.
He was excited that he could finally buy a piano.
John went to his favourite music store to buy a piano.
It was a store John had frequented for many years.
He was excited that he could finally buy a piano.
Coherence vs. Cohesioncoherence: structural, functional relations between sentences
cohesion: non-structural, text-forming relations that “tie” parts of discourse together
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John went to his favourite music store to buy a piano.
He had frequented the store for many years.
He was excited that he could finally buy a piano.
John went to his favourite music store to buy a piano.
It was a store John had frequented for many years.
He was excited that he could finally buy a piano.
Coherence vs. Cohesioncoherence: structural, functional relations between sentences
cohesion: non-structural, text-forming relations that “tie” parts of discourse together
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John went to his favourite music store to buy a piano.
He had frequented the store for many years.
He was excited that he could finally buy a piano.
He arrived just as the store was closing for the day.
John went to his favourite music store to buy a piano.
It was a store John had frequented for many years.
He was excited that he could finally buy a piano.
It was closing just as John arrived.
Coherence vs. Cohesioncoherence: structural, functional relations between sentences
cohesion: non-structural, text-forming relations that “tie” parts of discourse together
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John went to his favourite music store to buy a piano.
He had frequented the store for many years.
He was excited that he could finally buy a piano.
He arrived just as the store was closing for the day.
John went to his favourite music store to buy a piano.
It was a store John had frequented for many years.
He was excited that he could finally buy a piano.
It was closing just as John arrived.
Coherence vs. Cohesioncoherence: structural, functional relations between sentences
cohesion: non-structural, text-forming relations that “tie” parts of discourse together
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When Teddy Kennedy paid a courtesy call on Ronald Reagan recently, he made only one Cabinet suggestion. Western surveillance satellites confirmed huge Soviet troop concentrations virtually encircling Poland.(Hobbs 1982)
E: Forks have windows.P: Yes they do. Augmented pretension. Four plus four equals sixteen. It is a larger element, it’s photographic and phototrophic, but it is a higher number, higher course-work. It grows through evaporation or nocturnalism, it is sleepy, you rediscover it and I suppose forks could have windows through evaporation.
Coherence vs. Cohesioncoherence: structural, functional relations between sentences
cohesion: non-structural, text-forming relations that “tie” parts of discourse together
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Discourse modeling: intentional approach
discourse participants have certain goals (agendas) to achieve
utterances : actions that realize the intentions
speaker’s plan wrt. communicating intentions ties the discourse
together
discourse understanding : recognizing speaker’s intentions
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Intentional Approach (Grosz and Sidner 86)
three dimensions of discourse
linguistic structure : the utterances
intentional structure : hierarchy of intentions (communicative goals)
attentional structure : model of objects, properties and relationsthat are salient at each point in discourse
(dynamically changing)
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Intentional Approach (Grosz and Sidner 86)
Linguistic structure
discourse segments + relations that hold between them
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Intentional Approach (Grosz and Sidner 86)
Linguistic structure
discourse segments + relations that hold between them
(para-) linguistic expressions reflect discourse structure
cue phrases, aspect, tense, intonation, gesture
discourse structure constraints discourse interpretationanaphora resolution
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Intentional Approach (Grosz and Sidner 86)
Attentional structure
participants’ focus of attention (what is „attended to”)
modeled by focus spaces: objects and relations in focus
changes: insertion and deletion rules
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Intentional Approach (Grosz and Sidner 86)
Intentional structure
Discourse Purpose (DP)
purpose/intention held by discourse initiator e.g. make hearer:
intend to perform a task,
believe a fact,
believe that one fact supports another fact,
identify an object,
identify a property of an object
assumption: one per discourse
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Intentional Approach (Grosz and Sidner 86)
Intentional structure
Discourse Segment Purpose (DSP)
how given segment contributes to DP
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Intentional Approach (Grosz and Sidner 86)
Intentional structure
Hierarchy of intentions
dominanceDSP1 dominates DSP2 if satisfying DSP2 is intended to provide part of satisfaction of DSP1
precedence
DSP1 precedes DSP2 if DSP1 must be satisfied before DSP2
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Intentional Approach (Grosz and Sidner 86)
Intentional structure
Hierarchy of intentions
dominanceDSP1 dominates DSP2 if satisfying DSP2 is intended to provide part of satisfaction of DSP1
precedence
DSP1 precedes DSP2 if DSP1 must be satisfied before DSP2
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Discourse modeling: functional approach
relations between discourse units
relations may be made explicit by linguistic cues
model: domain-independent rhetorical structure
compositionally built discourse tree
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Rhetorical Structure Theory (Mann and Thompson 87)
nucleus(N) vs. satellite(S) segments core vs. peripheral part of the message
„nuclearity principle”
relations defined in terms of:constraints on the nucleus
constraints on the satellite
constraints on the comination of N and S
effect achieved on the text receiver
„classical RST”: 24 relations, (Mann, 2005): 30 relations
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Rhetorical Structure Theory (Mann and Thompson 87)
example relations
Elaboration: set/member, class/instance/whole/part…Contrast: multinuclearCondition: S presents precondition for NPurpose: S presents goal of action in NSequence: multinuclearResult: N results from something presented in S
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Rhetorical Structure Theory (Mann and Thompson 87)
Evidence: S provides evidence for what N claimsconstraints on N: Reader might not believe N to a degree satisfactory to Writer
on S: R believes S or will find it credible
on N and S: R's comprehending S increases R's belief of N
effect of W: R's belief of N is increased
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Rhetorical Structure Theory (Mann and Thompson 87)
Evidence: S provides evidence for what N claimsconstraints on N: Reader might not believe N to a degree satisfactory to Writer
on S: R believes S or will find it credible
on N and S: R's comprehending S increases R's belief of N
effect of W: R's belief of N is increased
[ George Bush supports Big Business. ]N
[ He is sure to veto House Bill 1711. ]S
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Rhetorical Structure Theory (Mann and Thompson 87)
(volitional) Cause: S presents a cause that motivates Nconstraints on N: N is a volitional action or else a situation that could have
arisen from a volitional action
on N and S: S could have caused the agent of the volitional action in N to perform that action; without the presentation of S, R might not regard the action
as motivated or know the particular motivation;N is more central to W's purposes than S.
effect of W: R recognizes S as a cause for the volitional action in N
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Rhetorical Structure Theory (Mann and Thompson 87)
(volitional) Cause: S presents a cause that motivates Nconstraints on N: N is a volitional action or else a situation that could have
arisen from a volitional action
on N and S: S could have caused the agent of the volitional action in N to perform that action; without the presentation of S, R might not regard the action
as motivated or know the particular motivation;N is more central to W's purposes than S.
effect of W: R recognizes S as a cause for the volitional action in N
[ George Bush supports Big Business. ]S
[ He is sure to veto House Bill 1711. ]N
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Problems with RST
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Problems with RST (cf. Moore and Pollack 92)
how many Rhetorical Relations are there?
how can we use RST in dialogue as well as monologue?
how to incorporate speaker’s intentions into RST?
RST does not allow for multiple relations holding between parts of a discourse
RST does not model overall structure of the discourse
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Computation of discourse coherence
grammar-basedanalogous to sentence grammar: encode RRs as rules, parse (Polanyi)
inference-basedproof-system: encode RRs as axioms, prove coherence, e.g. by abduction (Hobbs et al.)
plan-basedencode RRs as plan operators, instantiate plan given disourse goal (Litman&Allen)
shallow rules:schemata/templates, lexical clues (Marcu)
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Automatic identification of rhetorical structure (Marcu 99 and later work)
parser trained on a discourse treebank– 90 hand-annotated rhetorical structure trees
– Elementary Discourse Units (EDU) linked by Rhetorical Relations (RR)
– parser learns to identify N and S and their RR
– mainly shallow features: lexical, structural, Wordnet-based similarity
discourse segmenter (to identify EDUs)– trained to segment on hand-labeled corpus (C4.5)
– mainly shallow features: 5-word POS window, presence of discourse markers, punctuation, presence/absence of particular syntactic items
– 96-8% accuracy
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Automatic identification of rhetorical structure(Marcu 99 and later work)
evaluation of Marcu’s parser
hierarchical structure easier to identify than rhetorical structure
recall precision
EDU identification: 75% 97%
hierarchical structure (related EDUs): 71% 84%
nucleus/satellite labels: 58% 69%
rhetorical relation: 38% 45%
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Dialog
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Dialog
linguistic properties (cohesive devices)
structure manifested in the dialog partys’ contributions
speech-related phenomena:pauses and fillers („uh”, „um”, „..., like, you know,...”)
prosody, articulation
disfluencies
overlapping speech
spontaneous vs. „practical” dialogs
topic drifts vs. goal-orientedness
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Dialog
dialog is made up of turnsspeaker A says sth, then speaker B, then A...
how do speakers know when it’s time to contribute a turn?
there are points in dialog/utterance structure that allow for a speaker shift
Transition-Relevance Points (TRP)
e.g. intonational phrase boundaries
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Dialog
dialog is made up of turnsspeaker A says sth, then speaker B, then A...
turn taking rules determine who is expected to speak next
at each TRP of each turn:
if current speaker has selected A as next speaker, then A must speak next
if current speaker does not select next speaker, any other speaker may take next turn
if no one else takes next turn, the current speaker may take next turn
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Dialog
some turns specifically select who the next speaker will be
adjacency pairs
regularly occuring, conventionalized sequences
conventions introduce obligations to respond (and preferred responses)
greeting : greeting question : answer
complement : downplayer accusation : denial
offer : acceptance request : grant
set up next speaker expectations (‘significant silence’ dispreferred)
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Dialog
entering a conversation we (typically) have a certain intention
paradigmatic use of language: making statements...
...BUT there are also other things we can do with words
e.g. make requests, ask questions, give orders, make promises, give thanks, offer apologies
aspects of the speaker's intention:the act of saying something, what one does in saying it (requesting or promising)how one is trying to affect the audience
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Dialog: speech acts
certain actions we take in communication are designed to get our interlocutor(s) to do things on the basis of understanding of what we mean
doing things with words: Austin, 1962, later Searle, Davis speech acts
utterances are multi-dimentional acts that affect the context in which theyare spoken
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Dialog: speech acts
dimensions
locutionary act: uttering something with a certain „meaning”
illocutionary act: act performed by means of uttering the words utterance’s „conventional force”
perlocutionary act: what is brought about as a result (intentionally or not)
how hearer is affected: convincing the hearer,
persuading, surprising, making sad, laugh, etc.
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Dialog: speech acts
examples of illocutionary acts
assertive: get H to form or attend to a belief; e.g. „claim” „conclude”
directive: get H to do sth; e.g. „order”, „request”, „beg”
commissive: S commits to doing sth; e.g. „promise”, „plan”, „vow”, „bet”
expressive: S expresses a psychological state, feeling twrd. H „thank”, „apologize”, „hate”, „love”
declarations: S changes the state of the world; e.g. „resign”, „fire”, „name”, „baptize”, „pronounce husband and wife”
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Dialog: joint activity
when entering a conversation, we pressupose that there exists certain shared knowledge common ground
introduced by Stalnaker (1978) based on older family of notions: common
knowledge (Lewis, 1969), mutual knowledge or belief (Schiffler, 1972)
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Dialog: joint activity
when entering a conversation, we pressupose that there exists certain shared knowledge common ground
stock of knowledge taken for granted, i.e. assumed to be known both by the Speaker and the Hearersum of their mutual, common or joint knowledge, beliefs, and
suppositions
sources of the assumptions:evidence about social, cultural comunities people belong to, academicbackgrounds, etc. (communal common ground)
direct personal experiences (personal common ground)
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Dialog: joint activity
when entering a conversation, we pressupose that there exists certain shared knowledge common ground
What does it mean „You and I (mutually) know that p”?
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Dialog: joint activity
when entering a conversation, we pressupose that there exists certain shared knowledge common ground
What does it mean „You and I (mutually) know that p”?
I know that p You know that p
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Dialog: joint activity
when entering a conversation, we pressupose that there exists certain shared knowledge common ground
What does it mean „You and I (mutually) know that p”?
I know that p You know that p
I know that you know that p You know that I know that p
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Dialog: joint activity
when entering a conversation, we pressupose that there exists certain shared knowledge common ground
What does it mean „You and I (mutually) know that p”?
I know that p You know that p
I know that you know that p You know that I know that p
I know that you know that I know that p You know that I know that you know that p
...ad infinitum...
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Dialog: joint activity
communication relies on collaboration
Gricean Cooperative Principle + principles of rational behaviour
cooperatively interpret and contribute
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Dialog: joint activity
communication relies on collaboration
Gricean Cooperative Principle + principles of rational behaviour
cooperatively interpret and contribute
crucial: establishing shared knowledge (adding to common ground)
grounding
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Dialog: grounding
levels of interpretation of performed communicative act:channel: S executes, H attendssignal: S presents, H identifiesproposition: S signals that p, H recognizes that pintention: S proposes p, H considers p
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Dialog: grounding
levels of interpretation of performed communicative act:channel: S executes, H attendssignal: S presents, H identifiesproposition: S signals that p, H recognizes that pintention: S proposes p, H considers p
the Hearer must ground or acknowledge Speaker’s utterance OR signal, at the level that satisfies the Speaker, that there was a problemin reaching common ground
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Dialog: grounding
levels of interpretation of performed communicative act:channel: S executes, H attendssignal: S presents, H identifiesproposition: S signals that p, H recognizes that pintention: S proposes p, H considers p
grounding feedback possible at all levels:continued attentionrelevant next contributionacknowledgementdemonstration (e.g. paraphrase, completion)display (verbatim)
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Dialog: grounding
levels of interpretation of performed communicative act:channel: S executes, H attendssignal: S presents, H identifiesproposition: S signals that p, H recognizes that pintention: S proposes p, H considers p
problems ...possible at all levels:lack of perceptionlack of understandingambiguitymisunderstanding
clarification and repair strategies
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Dialog: grounding
levels of interpretation of performed communicative act:channel: S executes, H attendssignal: S presents, H identifiesproposition: S signals that p, H recognizes that pintention: S proposes p, H considers p
S: I can upgrade you to an SUV at that rate.H gazes appreciatively at S (continued attention)
H: Do you have a RAV4 available? (relevant next contribution)
H: ok / mhmmm / Great! (acknowledgement/backchannel)
H: An SUV. (demonstration/paraphrase)
H: You can upgrade me to an SUV at the same rate? (display/repetition)
H: I beg your pardon? (request for repair)
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goal-oriented conversational systems
challenges:
need to understand
interpretation context-dependent
intention recognition
anaphora resolution
people don’t talk in sentences...
user’s self-revisions
dialog systems
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goal-oriented conversational systems
how:
interactions in a limited domain
prime users to adopt vocabulary the system knows
partition interaction into manageable stages
let the system take the initiative (predictability)
dialog systems
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example tasks:
retrieve information information-seeking dialogue
seek to satisfy constraints negotiation dialogue
perform action command-control dialog
collaborate on solving a problem problem-solving dialog
instruct tutorial/instructional dialogue
dialog systems
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modality: type of communication channel used to convey or acquire information
natural-language: spoken or textual keyboard-based or both
pointing devices
graphics, drawing
gesture
combination of one of more of above (multi-modal systems)
dialog systems
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turn-taking and initiative strategies
system initiativeS: Please give me your arrival city name.
U: Baltimore.
S: Please give me your departure city name….
user initiativeS: How may I help you?
U: I want to go from Boston to Baltimore on November 8.
mixed initiative
S: How may I help you?
U: I want to go to Boston.
S: What day do you want to go to Boston?
dialog systems
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ResponseGeneration
Automatic SpeechRecognition
Spoken LanguageUnderstanding
DialogManagement
data,rules,
domain reasoning
Speech
Action
Words spoken
Bill: I need a flight from Washington DC to Denver roundtrip
Meaning
Speech
ORIGIN_CITY: WASHINGTONDESTINATION_CITY: DENVERFLIGHT_TYPE: ROUNDTRIP
getDepartureDate
System: Which date do you want to fly from Washington to Denver?
dialog systems
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NLP: grammars, parsers,generation, discourse,
pragmatics
AI: reasoning, communication,planning, learning
human factors: design, performance, usability
speech technology:recognition, synthesis
hello Bill, how may I help you today?
dialog systems
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dialog management
control the flow of dialog
when to say something, when to listen (turn-taking), when to stop
update dialog context with current user’s input and output the next
action in the dialog
deal with barge-in, hang-ups
dialog modeling
what is the context
what to say next
goal: achieve an application goal in an efficient way through a series of interaction with the user
dialog systems
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12 październik 2006 bruckenkurs – text structure and dialogue 81/71
`When I use a word,' Humpty Dumpty said, in rather a scornful tone, `it means just what I choose it to mean – neither more nor less.' `The question is,' said Alice, `whether you can make words mean so many different things.' `The question is,' said Humpty Dumpty, `which is to be master – that's all .‘
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References
D. Byron. Resolving Pronominal Reference to Abstract Entities. Proceedings of ACL-02, pp.80–87, 2002
B. J. Grosz, K. Sparck-Jones, B. L.. Webber. Readings in Natural Language Processing, Morgan Kaufmann Publishers, 1986
B. J. Grosz and C. L.. Sidner. Attention, intentions, and the structure of discourse. Computational Linguistics 12(3):175–204. 1986
M. Halliday, R. Hasan. Cohesion in English. Harlow: Longman, 1976
J. Hobbs. Towards an Understanding of Coherence in Discourse, in W. Lehnert & M. Ringle (eds.), Strategies for Natural-Language Processing, Hillsdale NJ: Erlbaum, 1982
W. C. Mann and S. A. Thompson. Rhetorical structure theory: A theory of text organization. Technical Report ISI/RS-87-190, USC/ISI, 1987
D. Marcu. A decision-based approach to rhetorical parsing. Proceedings of ACL-99, pp. 365–372, 1999
B. L.. Webber. Discourse deixis: Reference to discourse segments. Proceedings of ACL-88, pp. 113–123, 1988
E.B. White. Letters of E.B. White, ed. D.L. Guth, Harper & Row, New York, 1972 (example sentences with anaphora)