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CPE 641 Natural Language Processing

CPE 641 Natural Language Processing. HPSG II Asst. Prof. Nuttanart Facundes, Ph.D. HPSG. Highly structured representation of grammatical categories, encoded as typed feature structures. A set of descriptive constraints on the modeled categories expressing linguistic generalizations.

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CPE 641 Natural Language Processing

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  1. CPE 641 Natural Language Processing HPSG II Asst. Prof. Nuttanart Facundes, Ph.D.

  2. HPSG • Highly structured representation of grammatical categories, encoded as typed feature structures. • A set of descriptive constraints on the modeled categories expressing linguistic generalizations.

  3. HPSG Theory Consists of: • A lexicon licensing basic words • Lexical rules licensing derived words • Schemata licensing phrases • Statements about word/constituent order • Other rules/principles

  4. Basic Lexical Entry

  5. Phrasal Structures

  6. Declarative characterization of natural language • HPSG uses ‘ontology’ – declaration of what exists • It uses ‘type hierarchy’, defining which type has which appropriate attributes with which appropriate values.

  7. Expressing the theory • HPSG theory is specified using a specific description language. (AVMs)

  8. Semantics in HPSG • Encoded as the value of CONTENT feature • Based on ‘event semantics’

  9. Minimal Recursion Semantics (MRS) • MRS semantics was developed to provide meaning representations which do not force scope ambiguities to be resolved. • MRS is also useful to keep track of how much meaning remains to be encoded or decoded in generating sentences.

  10. MRS representation • MRS representation of John makes pizza

  11. MRS is a representation of the meaning of expressions as a set of Elementary Predications (EPs). • An EP contains a semantic relation and argument(s) associated with that relation.

  12. MRS features & values

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