DOC PREVIEW
Columbia COMS W4705 - Information Status

This preview shows page 1-2-17-18-19-35-36 out of 36 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 36 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

Information StatusVarieties of Information StatusToday: Given/NewWhy do we care about the given/new distinction?Defining Given/NewPrince ’81: A Given/New TaxonomySlide 7Slide 8Given/New and Definiteness/IndefinitenessWhat’s wrong with a simple Hearer-centric model of given/new?Slide 11What does this new Hearer/Discourse given/new distinction provide?Gross Oversimplification: Given Items Tend to be DeaccentedHow can we determine automatically whether a discourse entity is given or new?Boston Directions Corpus (Hirschberg & Nakatani ’96)Slide 16Slide 17Hearer and Discourse Given/New LabelingWhat could we do with this labeled data?Does Given/New Status Predict Deaccenting?What else might be at work?Experimental DesignSlide 23Slide 24Slide 25Slide 26Slide 27Slide 28Experimental ConditionsProsodic AnalysisGrammatical Role/Surface Position AccentingFindingsHow can we explain these observations?Given/New Sensitive to the Role the Discourse Entity PlaysConsequences for NLPNext ClassInformation StatusVarieties of Information Status–Contrast John wanted a poodle but Becky preferred a corgi.–Topic/comment The corgi they bought turned out to have fleas.–Theme/rheme The corgi they bought turned out to have fleas.–Focus/presupposition It was Becky who took him to the vet.–Given/new Some wildcats bite, but this wildcat turned out to be a sweetheart.Today: Given/New•Why do we care about Given/New?•Defining Given/New: why is this hard?–Hearer-based and Discourse-based models•Uses of Given/New information in NLP•Identifying Given/New information automatically–Rule-based–Corpus-based–The Boston Directions Corpus–Laboratory studies suggest new directionsWhy do we care about the given/new distinction?•Building a model of the discourse–What do S and H believe to be true?–What is in their consciousness now?–What is ‘grounded’?•Speech technologies–TTS: Given information is often deaccented while new information is usually accented–ASR?Defining Given/New•Halliday ‘67:–Given: Recoverable from some form of context–New: Not recoverable•Chafe ’74 ’76:–Given: what S believes is in H’s consciousness–New: what S believes is not…–“Chafe-givenness”Yesterday I had my class disrupted by a bulldog/dog.I’m beginning to dislike dogs/bulldogs.•But not vice versa….Prince ’81: A Given/New Taxonomy•Text as set of instructions from S to H on how to construct a discourse model–Model includes discourse entities, attributes, and links between entities–Discourse entities: individuals, classes, exemplars, substances, concepts (NPs)–Entities as ‘hooks’ on which to hang attributes (Webber ’78)•Entities when first introduced are new–Brand-new (H must create a new entity)I saw a dinosaur today.–Unused (H already knows of this entity)I saw your mother today.•Evoked entities are old -- already in the discourse–Textually evokedThe dinosaur was scaley and gray.–Situationally evokedThe light was red when you went through it.•Inferrables–ContainingI bought [a carton of eggs]. One of them was broken.[The door of the Bastille] was painted purple.–Non-containingA bus pulled up beside me. The driver was a monkey.Given/New and Definiteness/Indefiniteness–Definiteness: subject NPs tend to be syntactically definite and old–Indefiniteness: object NPs tend to be indefinite and newI saw a black cat yesterday. The cat looked hungry.•Definite articles, demonstratives, possessives, personal pronouns, proper nouns, quantifiers like all, every signal definiteness…but…There were the usual suspects at the bar.•Indefinite articles, quantifiers like some, any, one signal indefiniteness…but….This guy came into the roomWhat’s wrong with a simple Hearer-centric model of given/new?•Hearer-centric information status:–Given: what S believes H has in his/her consciousness–New: what S believes H does not have in his/her consciousness•But discourse entities may also be given and new wrt the current discourse–Discourse-old: already evoked in the discourse–Discourse-new: not evoked(1) A: I’ve decided to make an appointment with Lee Bollinger. (2) B: Why do you want to see Bollinger?•Hearer status of discourse entities in 1? 2?–If B is your roommate? your mother? a guy on the subway?•Discourse status of discourse entities in 1? 2?•What would be the hearer/discourse status of discourse entities in this version?(1) A: I’ve decided to make an appointment with Lee Bollinger. (2a) B: Why do you want to see the president?(2b) B: Have you talked to his secretary?What does this new Hearer/Discourse given/new distinction provide?•A way to separate what is explicit in the discourse model from what is believed to be in speaker/hearer cognitive model•A way to explain given/new in more complex terms–To identify coreference relations–To explain deaccenting in ASR and TTSGross Oversimplification: Given Items Tend to be Deaccented•Accenting and deaccenting: making items intonationally prominent or not•Critical to get this distinction ‘right’ in TTS–Accenting everything makes it hard for people to understand anything, e.g.I like my cat and my cat adores me.One potato, two potato, three potato,…If a discourse entity is given for one speaker then it may or may not be given for another speaker.How can we determine automatically whether a discourse entity is given or new?•A rule-based approach:–Stem the content words in the discourse–Select a window within which incoming items with the same stem as a previous entity and within this window will be labeled ‘given’•Other items are ‘new’•Is this hearer-based? Discourse-based?•How well does it work? –65-75% accurate (precision) depending on genre, domainBoston Directions Corpus (Hirschberg & Nakatani ’96)•Experimental Design•12 speakers: 4 used•Spontaneous and read versions of 9 direction-giving tasks•Corpus: 50m read; 67m spon•Labeling–Prosodic: ToBI intonational labeling–Discourse: Grosz & Sidner–Given/new (Prince ’92), grammatical function, p.o.s.,…d1: dsp1: step 1: enter and get tokenfirstenter the Harvard Square T stopand buy a tokend2: dsp2: inbound on red linethenproceed to get on theinboundumRed Lineuh subwayBoston Directions Corpus: Describe how to get to MIT from Harvarddp3 dsp3: take subway from hs, to cs to ksandtake the subwayfrom Harvard Squareto Central Squareand then to Kendall Squaredp4:


View Full Document

Columbia COMS W4705 - Information Status

Download Information Status
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Information Status and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Information Status 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?