CS 544: Lecture 3.1Problems in Discourse

Jerry R. Hobbs

USC/ISI

Marina del Rey, CA

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

Is There Systematicity?

The basic unit of information is the predication:

p(x,y)What is p? predicate

strengtheningWhat are x and y?

coreference

What’s 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)

What’s the relation between these two predications?intraclausal coherence, discourse coherence

(predicate strengthening on sentence adjacency)

What is the Predicate?

Interpreting compound nominals: feeder texts => feeder(x,y) & nn(y,z) & text(z) Harvard protocircuitry, chocolaty mess, face value

Interpreting possessives: its predecessors’ trainings, my texts, H’s 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.

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: <conflict in previous 173 pages> .... 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)

Why this Predicate with this Argument?

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 q(x) where p(x) --> q(x)

p(x) interpreted as p(f(x))

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

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: ... wasn’t rule-based. We could not estimate how many “facts”... We could not estimate.... But ... insights.

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.”

Aim of this Part of Course

To learn to recognize these problemsand to get some idea about how they

might be approached.