Linguistics
Computational Sentence and Discourse Semantics
Pre-requisites: Computational Syntax and Semantics
Course Description
The focus in this graduate course is on computational issues in the construction and manipulation logical representations of the semantics of sentences and discourse. The course will take students step by step by through the semantic components of a unification-based natural language understanding system, including the compositional semantic rules, the integration of syntactic and semantic processing, pragmatic resolution in context, and translation to application semantics. Topics covered will include quantifiers and quantifier scope, anaphora, ellipsis, reference resolution, and conjunction. Students will be expected to choose a research topic, read the relevant journal articles, and complete a short research paper, which may or may not incorporate a programming project.
Required reading: Alshawi, H. (1992). The Core Language Engine Bradford. Cambridge.
A packet of journal and conference articles.
Grading
Assignments (40%)
Research Paper (60%).
Week 1:
Review of semantics in unification grammar. Combined syntax and semantics rules.Week 2,3:
Quantification. First order and non-first order quantifiers. Scope ambiguity. Algorithms for scope disambiguation. Scope-neutral semantic representations.Weeks 4,5:
Survey of basic constructions and their compositional semantics: relative clauses, conjunction, control and raising verbs, axuiliaries.Week 6:
Selectional restrictions through sort hierarchies and sortal rules. The Core Language Engine (Alshawi 1992) implementation.Week 7:
Selectional restrictions as a filter on syntactic analyses during parsing. The Gemini approach (Dowding And Moore 1994).Weeks 8,9:
Pronominal anaphora. Interactions of anaphora and quantification. Strict/sloppy ambiguities. Geach's pronouns of laziness. E-Type Pronouns.Week 10:
Algorithms for anaphora resolution. The Lappin and Leass (1994) and Hobbs (1978) algorithms. Centering theory.Week 11,12:
Ellipsis. Sag/Gawron/Peters approach to verb phrase ellipsis. Higher Order Unification. Kehler's work on discourse effects.Week 13,14:
Resolution by abduction. Treatments of anaphora, reference resolution, and ellipsis interpretation. Gricean resolution.Week 15:
Translation to application semantics. Abductive translation rules (Rayner 1992).