CS 544: Lecture 3.1 Problems in Discourse

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CS 544 Lecture 3.1Problems in Discourse

• Jerry R. Hobbs
• USC/ISI
• Marina del Rey, CA

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Outline of Next 6 Lectures

• 1. Interpretation problems in discourse
• A typology of sorts
• 2. Interpretation problems in discourse
• Examples in the target texts
• 3. All of syntax and compositional semantics
• 4. Interpretation as abduction and local
  pragmatics
• problems MiniTacitus
• 5. Discourse coherence
• 6. Linking with known theory or set of interests

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Is There Systematicity?
The basic unit of information is the
predication
p(x,y)
What is p? predicate strengthening
What are x and y? coreference
Whats the relation between p and x, p and y? In
what way is it appropriate for p to describe x?
y? metonymy, metaphor, ...
p(x,y) q(y,z)
Whats the relation between these two
predications? intraclausal coherence, discourse
coherence (predicate strengthening on sentence
adjacency)
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What is the Predicate?
Interpreting compound nominals feeder texts
gt feeder(x,y) nn(y,z) text(z) Harvard
protocircuitry, chocolaty mess, face
value Interpreting possessives its
predecessors trainings, my texts, Hs
simple-mindedness Interpreting of
paraphrase of text predicate-argument
relation Interpreting other prepositions
organizing in upheavals, sense from the
insensate Interpreting other underspecified
predicates acquire facts, got a
reading Text gives us general predicates that we
understand specifically.
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What is the Argument?Coreference
Pronouns H .... It .... I .... We ....
Lentz .... He .... ... itself ... English
was a mess, it began to dawn on me. Definite
noun phrases Anaphoric ltconflict in
previous 173 pagesgt .... the problem
Determinative the knowledge H had
inherited Even indefinite noun phrases
diagramming tasks.... a simple story ....
rule-based .... facts ..... Implicit
arguments Native speakers (of English)
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Why this Predicate with this Argument?
p(x) interpreted as q(x) where p(x) --gt q(x)
Finding relevant aspect of predicate
hideous diagramming tasks knowledges
setOf(knowledge) Metaphor interpretation
wringing sense out of insensate ..., it began to
dawn on me English was a chocolaty mess
shattered visage of English Metonymy
interpretation The missionary ...
produced ... alternatives. protocircuitry
missed story keeps H paraphrasing
p(x) interpreted as p(f(x))
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Clause-Internal Coherence
Relations that go beyond the predicate-argument
relations conveyed by syntactic
structure my ... feeder texts my I
give H text feeder I feed H text so H will
grow crude but increasingly specific
contrast index, access and arrange similar
computational operations inherited from
predecessors trainings predecessor
defeasibly implies inherit
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Discourse Coherence
Relations between successive segments of
discourse are typically varieties of
rephrasing/elaboration H was learning.
Organizing itself in upheavals. similarity
and contrast, generalization and
examplification How to index ...
remained the problem. But H was learning.
Paragraphs 3 and 4 General. Specific.
Specific. background (figure-ground)
successive changes of state, occasion
... it dawned on me. I wondered ...
causality, enablement, violated causality or
implication ... wasnt rule-based. We
could not estimate how many facts...
We could not estimate.... But ... insights.
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Situating Text w.r.t. a Background Theory
Often an important part of understanding a text
is anchoring it in a background theory,
e.g. Chapter 3 in Chapter 2 of a textbook. In
this text, much depends on anchoring examples in
a background theory of parsing and
ambiguity The missionary was prepared to
serve. Time flies like an arrow.
Help set implied precedents in sentences with
ambiguous parts. The trainer talked to the
machine in the office with a terminal.
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Aim of this Part of Course
To learn to recognize these problems and to get
some idea about how they might be approached.