Discourse Structure in GenerationTodayIs there structure in this discourse?Is this a reasonable structure?This?Slide 6What information do we use in segmenting a discourse?Structures of Discourse Structure (Grosz & Sidner ‘86)Linguistic StructureLinguistic Structure of Discourse DIntentional StructureSlide 12Slide 13Attentional State: The Focus StackSlide 15Limits of the TheoryHow might people recognize discourse structure?Acoustic and Prosodic Cues to Discourse StructureProsodic Correlates of Discourse/Topic StructureSlide 20IssuesGrosz & Hirschberg ‘92Slide 23Slide 24Next01/14/19 1Discourse Structure in GenerationJulia HirschbergCS 470601/14/19 2Today•Models of Discourse Structure–Do we have them?–Grosz & Sidner ’86•What identifies discourse structure to Hearers?–Textual cues–Spoken cues•How can we produce appropriate discourse structure in TTS systems?•Can we identify discourse structure automatically, from speech?01/14/19 3Is there structure in this discourse?A beautiful mallard spotted the dove I was feeding.The duck dove supply is small this year.That dove was history in a minute.Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.To my surprise, I ran into a friend from back home. When I told her of my recent experience she questioned my sanity.01/14/19 4Is this a reasonable structure?A beautiful mallard spotted the dove I was feeding.The duck dove supply is small this year.That dove was history in a minute.Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.To my surprise, I ran into a friend from back home. When I told her of my recent experience she questioned my sanity.01/14/19 5This?A beautiful mallard spotted the dove I was feeding.The duck dove supply is small this year.That dove was history in a minute.Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.To my surprise, I ran into a friend from back home. When I told her of my recent experience she questioned my sanity.01/14/19 6This?A beautiful mallard spotted the dove I was feeding.The duck dove supply is small this year.That dove was history in a minute.Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.To my surprise, I ran into a friend from back home. When I told her of my recent experience she questioned my sanity.01/14/19 7What information do we use in segmenting a discourse?•‘Topic’ coherence?•Repeated reference?•‘Cue’ phrases?•????01/14/19 8Structures of Discourse Structure (Grosz & Sidner ‘86)•A leading theory of discourse structure–Based upon Speaker intentions and Speaker and Hearer attentional state–Identifies a few, general relations that hold among Speaker intentions–Identifies a model of attentional state•Three components:–Linguistic structure–Intentional structure–Attentional structure01/14/19 9Linguistic Structure•What is actually said or written•How is the linguistic structure represented?–Assume discourse is segmented into Discourse Segments (DS) •What is the basic unit of analysis?•Do we all segment alike?•Do we all use the same cues?01/14/19 10Linguistic Structure of Discourse DS1: A beautiful mallard spotted the dove I was feeding.The duck dove supply is small this year.That dove was history in a minute.S2: Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.To my surprise, I ran into a friend from back home. When I told her of my recent experience she questioned my sanity.01/14/19 11Intentional Structure•Discourse purpose (DP): basic purpose of the Speaker in producing the discourse•Discourse segment purposes (DSPs): the Speaker’s purpose in producing the segment•Segments are related to one another by their purposes:–Satisfaction-precedence: DSP1 must be satisfied before DSP2–Dominance: DSP1 dominates DSP2 if fulfilling DSP2 constitutes part of fulfilling DSP101/14/19 12Linguistic Structure of Discourse DDSP1: Describe murder of dove by duck.S1: A beautiful mallard spotted the dove I was feeding.The duck dove supply is small this year.That dove was history in a minute.DSP2: Describe meeting of old friend.S2: Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.To my surprise, I ran into a friend from back home. When I told her of my recent experience she questioned my sanity.01/14/19 13DSP2: Describe recovery process.S2: DSP3: Describe snackS3: Well, to recover from this horrible scene, I went to the park snack bar for a cup of cocoa.DSP3: Describe meeting old friend.S4: To my surprise, I ran into a friend from back home. DSP5: Describe friend’s reactionS5: When I told her of my recent experience she questioned my sanity.01/14/19 14Attentional State: The Focus Stack•Stack of focus spaces, each containing objects, properties and relations salient during each DS, plus the DSP•State changes: transition rules controlling the addition/deletion of focus spaces–Information at lower levels may or may not be available at higher levels–Focus spaces are pushed onto the stack when•A new DS is begun01/14/19 15•An embedded DS (e.g. a DS dominated by another DS) is begun–Focus spaces are popped when they are completed•State of focus stack models felicitous reference, coherence in discourseS2: DSP2, scene, Speaker, snack_barCocoa, friend, home,sanityS1: DSP1, duck, dove, Speaker, duck_dove_supply01/14/19 16Limits of the Theory•Assumes discourses are task-oriented•Assumes a single, hierarchical structure shared by S and H•Questions:–Do people really build such structures when they converse? –Use them in interpreting what others say?–How could they do it?01/14/19 17How might people recognize discourse structure?•Linguistic markers?–tense and aspect–cue phrases•Inference of Speaker intentions?•Inference from task structure?•Intonational Information?01/14/19 18Acoustic and Prosodic Cues to Discourse Structure•Intuition:–Speakers vary acoustic and prosodic cues to convey variation in discourse structure–Systematic? In read or spontaneous speech?•Evidence: –Observations from recorded corpora–Laboratory experiments–Machine learning of discourse structure from acoustic/prosodic features01/14/19 19Prosodic Correlates of Discourse/Topic Structure•Pitch rangeLehiste ’75, Brown et al ’83, Silverman ’86, Avesani & Vayra ’88, Ayers ’92,