CS 544: Lecture 3.1 Problems 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 strengthening What 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:.... 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 problems and to get some idea about how they might be approached.