101 uses for information structure
(It’s not just for prosody you know!)
Taal- en spraaktechnologie
Fall 2005
Lecture 2
Jennifer Spenader
1
Structure of lecture
1.
Is there really only one way to define new-given?
•
2.
In depth look at one theory of new-given (Prince 1981)
How does new-given relate to choice of lexical and
syntactic form?
•
Definite vs. indefinite forms
–
•
3.
What appears as a subject ?
(in information structural terms)
How do we interpret underspecified forms?
•
•
4.
Marking with particles
Resolution of anaphoric reference
Interpretation of bridging NPs
Why is this useful?
2
New-given revisited
3
New and Given (Prince 1981)
“…the Old/New Information
Workshop held at
Urbana, Summer 1978,
was quickly and quite
appropriately dubbed
“The Mushy Information
workshop” “
Mushy peas
4
Different definitions
are the big names in new-given research but
– They are all using same terms but slightly different
definitions that make different categorizations
5
Predictability/Recoverability
• GIVENESS AS PREDICTABILITY/RECOVERABILITY
– The speaker assumes that the hearer can predict or could
have predicted that a particular linguistic item will or would
occur in a particular position within a sentence
• Most similar to Kuno’s definition
Ex. (Prince 81:226)
(1) Mary paid John and he/*0 bought himself a new coat.
(2) John paid Mary and he/0 bought himself a new coat.
• Deletability coincides with predictability, yet we don’t
want to consider “he” in (2) old, but in (1) new.
6
Saliency
• GIVENESS AS SALIENCY
– The speaker assumes that the hearer has or could
appropriately have some particular thing/entity/… in her
consciousness at the time of hearing the utterance
• Salient to the hearer
• Close to Chafe’s definition of givenness
(3) I saw your father yesterday.
(4) I saw a two-headed man yesterday.
• Chafe’s definition would treat both referents as new.
7
Saliency: examples
(5) We got some picnic supplies out of the trunk.
The beer was warm.
• Bridging anaphors (associative anaphors) would also
be treated as new.
• But Chafe also claims that only given items can be
pronominalized. This seems to be wrong if you don’t
allow inferred referents to be given, e.g.:
(6) Harry threw up and Sam stepped in it.
8
Shared knowledge
• GIVENESS AS SHARED KNOWLEDGE
The speaker assumes that the hearer “knows”,
assumes, or can infer a particular thing (but not
necessarily thinking about it).
• Most similar to Clark & Haviland’s definition
– Inferred referents, such as “the beer” would be given
(7) Where were your grandparents born?
9
How are all three ideas related?
• If a speaker thinks the hearer can predict something,
then the speaker must also believe the hearer has
this element in their conscious mind
• If a hearer has something in their conscious mind,
then it isn’t so far fetched to believe that they can
draw inferences based on it…
10
11
Basically all
these theories
claim that
speaker’s actively
try to take the
hearer’s knowledge
into account…
…but actually
there might be
some sort
advantage for the
Speaker
12
ASIDE:
Discourse vs. Word Jumbles
• A discourse is different from a collection of words or
sentences because it has coherence
• Coherence is manifested in logical progressions of
ideas, continuation of topics, appropriate choice of
reference that distinguishes new information from old
• A discourse can be a dialogue, monologue or written
text
13
ASIDE:
Discourse Model
• Understanding a discourse in part involves building a
discourse model of the information contributed
• This includes keeping track of the discourse referents
brought up in the discourse, including:
–
–
–
–
How activated they are
What attributes they have
Links between them
(cf. Discourse Representation Theory)
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Assumptions used to choose form
“From the point of view of a speaker/writer, what
kinds of assumptions about the hearer/reader
have a bearing on the form of the text being
produced…” (Prince 81:233)
15
Assumed Familiarity
Assumed familiarity
New
Brand-new
Inferrable
Evoked
Unused
Inferrable
Brand-new
Brand-new
(Unanchored) Anchored
Inferrable
Inferrable
Inferrable
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Examples of Assumed Familiarity
(8) I bought a beautiful dress. (Brand-new + attribute)
(9) A rich guy I know bought a Cadillac. (Brand-new Anchored
+ attribute)
(10) I went to the post office and the stupid clerk couldn’t’ find a
stamp. (Inferrable + attribute)
(11) Have you heard the incredible claim that the devil
speaks English backwards? (Containing inferrable + attribute)
(12) Susy went to visit her grandmother and the sweet lady was
making Peking Duck (Evoked + attribute)
(13) Hi, I’m home. (Situationally evoked)
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Points
• This new taxonomy of new-given introduces a
large number of distinctions
– Are these distinctions necessary?, E.g.
– Do they correlate with different linguistic or
prosodic forms?
– Are they perceived by hearers? Consistently?
18
ASIDE:
Higher level categories
• Linguistic categories like parts-of-speech are
generally easy to identify
– It’s simple to define what nouns and verbs are for
most languages
• Most syntax, once a theory is agreed upon,
can be consistently categorized
– i.e. we can all recognize noun phrases with a very
high
19
ASIDE:
Verifying higher level categories
• But for things like information structure or
speech acts, it’s not as clear what categories
actually exist
• Annotation experiments:
– A high degree of agreement between annotators is
taken as evidence that the categories identified
are cognitively real
20
Definites and anaphors
Correlations with new-given statuses
21
What does a
referentially “bad” text
look like?
I live in a house in
Gronveldstraat 16.
A house in Gronveldstraat
16 was renovated a few
years ago.
The landlord put in central
heating and fixed the
front of a house in
Gronveldstraat 16.
Then a house in
Gronveldstraat 16 looked
really nice.
22
What makes a text
referentially better?
I live in a house in
Gronveldstraat 16.
The house was renovated a
few years ago.
The landlord put in central
heating and fixed the
front of the house.
Then it looked really nice.
23
Another BAD text
• A man came into the bar. The bartender
began to talk to a man.
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Referents semantically
• Referents are the actual entities in our discourse
model
• Two types of referential forms available
– indefinite reference
• introduce new referents with indefinite reference
– definite reference
• subsequent mention is done with definite reference
25
indefinite vs. definite
• indefinite noun phrases
– “a man”, “some children”
• Indefinites tend to be used to introduce new
referents
– So can be considered a morphological form for
new information
26
Formal Definiteness
• Formal property of NPs (decidable on form alone)
• Formal definiteness: Marking of the NP
–
–
–
–
–
–
Definite articles (the, de, het)
Demonstrative articles (deze, dit)
Possessive adjectives (jouw, jullie, mijn…)
Personal pronouns (je, jij, ik, hij, zij, hem, haar)
Unmodified proper nouns (Esther, Petra)
Certain quantifiers argued to be definite (all, every)
27
Simple indefiniteness to definiteness
RULE:
1. Introduce items with full, indefinite noun phrases.
2. Later, refer to them with definite noun phrases
3. Later, as long as it doesn’t lead to confusion, you
can refer with pronouns
(Ex) I live in a house in Gronveldstraat 16.
The house was renovated a few years
ago. It looks great.
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Interpretation
• E.g. DRT
– Indefinite noun phrases introduce a new discourse
referent
– Definite noun phrases trigger a search for an
already given definite referent that can serve as
an antecedent
– Pronouns also trigger a search for a compatible
antecedent
29
Definiteness correlates
•
Definiteness correlates with other linguistic forms
1. Subjects tend to be definite (Prince 1981, Prince
1993)
2. Only indefinites can occur as the object in There –
sentences (Ex. From Prince 1993)
(Ex)
A/The man was in the room.
There was a man/the man in the room.
30
There-sentences
(5) a. There were the same people at both
conferences.
b. There was the usual crowd at the beach.
c. There was the stupidest article on the reading
list.
Revised claim: Some definites are not actually definites
.
31
Conceptual Definiteness
• Definite referents are given in some way
– They are recognizable, or familiar?
– They are specific, or identifiable?
– They are unique in their context, and thus
identifiable (logical definition)
• Formal definiteness and conceptual
definiteness don’t always coincide
32
Not definiteness, but givenness
• Prince (1993)’s claim: There-sentences don’t require indefinites.
There-sentences require hearer-new referents
(5) a. There were the same people at both conferences.
b. There was the usual crowd at the beach.
c. There was the stupidest article on the reading list.
Definiteness: marks identifiable, specific or unique for the speaker,
but the There-sentence for marks the awareness that it is
hearer-new
33
Generalizations
• Indefinites tend to be used to introduce hearer-new
information (discourse-new)
• Definites are used for discourse-given information
• Definites are sometimes used for speaker known,
speaker specific, items, not necessarily known to the
hearer.
34
Simplification!!!
• And of course, there are many exceptions to
what can be marked as definite
• Given in some way = licenses marking
35
New entities introduced with definite
Greta walked slowly through the woods. She
enjoyed the stillness.
36
Anaphoric reference to abstract objects
Greta slowly made her way along the path
breathing deeply.
However, it wasn’t enough to quiet her troubled
thoughts.
37
Inferrables introduced with definite reference
The sky lit up with lightening and thunder,
rumbling in a threatening way. The storm
was getting closer.
38
From generation to interpretation
• Until now we’ve been looking at things from
the perspective of the speaker
• What about in interpretation? What does the
hearer need to do with a definite noun phrase
or a pronoun?
– RESOLVE IT!
39
Features?
• For NLP = easy to identify features
– gender
– number
– recency
• 90% of pronominal referents have antecedents in the
same or preceeding sentence
– parallelism
– semantic information
– saliency:
• does the referring expression seem to be specifying
something in focus?
40
World knowledge
World knowledge supports anaphoric resolution
(Ex)
The mother dressed her dotter.
Afterwards she fed her.
Who fed who?
41
World Knowledge 2
(from Sayed, Issues in Anaphor Resolution,
http://nlp.stanford.edu/courses/cs224n/2003/fp/iqsayed/project_report.pdf)
(Ex)
There were dresses of several different colors
and styles.
They were all pretty, labeled with price tags.
Sally chose a blue one. Mary chose a
skimpy one.
42
Ambigous, but we have preferences
(From Beaver, 2003)
(Ex)
(Ex)
a. Jane likes Mary .
b. She often goes around for tea with her.
c. She chats with the young woman for ages.
c’. SHE chats with the young woman for
ages.
a. John hit Martin.
b. He fell.
c. HE fell.
43
Non-referring NPs…
Ex.
Little Johnny threw up and then stepped in it.
Ex.
John became a guitarist because he thought
that it was a beautiful instrument.
44
Associative (Bridging) anaphora
We took the picnic things out of the trunk.
The beer was warm.
Gerlof entered the ballroom.
The chandelier sparkled brightly.
45
Resolving Bridging Anaphora
• Requires access to lexical information!
• This is what we will talk about NEXT time!
– What type of lexical information is relevant to
language processing?
– What type of computational lexical resources exist
• Why are they formed the way they are?
• What can they be used for?
46
Applications that benefit from
anaphor resolution
• Information extraction systems
– Pre-med PULS Medical extraction system
• Question-Answer systems
– As a subset of information retrieval systems
• Automatic Summarization systems
– As a way to make information search more
efficient
– Swe-sum
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Prosody: When, where, why?