CSCI 587 - Lecture 14 Features

• Chart parsing example finished
• Features: Example * a boys
• Subject Verb number agreement
• Feature - additional information attached to constituents in a parse
• sample features
  • NUMBER
  • ROOT
  • CAT
• Feature Structure Examples

  ART1 : (CAT art         or more         ART1: (art ROOT a NUMBER s)
          ROOT a          concisely       
          NUMBER s)
  
  the NP "a blue Kentucky fan"                   NP "the Gamecocks"
  NP1 : ( NP NUMBER s                     NP2: (NP NUMBER p
          1 ( art ROOT a NUMBER s)                 1 (art ROOT the)
          2 ( adj ROOT blue)                       2 (n ROOT Gamecock NUMBER p)
          3 ( adj ROOT Kentucky )               )
          4 ( n   ROOT fan NUMBER s)
        )
  

• Article-Noun agreement: (NP NUMBER ?n) -> (art NUMBER ?n) (n NUMBER ?n)
• Variables / Constrained Variables: (n ROOT fish NUMBER ?n{s,p})
• Basic Feature Systems for English
  • Number and person
  • Verb-Form
  • Prepositional phrases
• AGR : {1s,2s,3s,1p,2p,3p}
• Verb Form and Subcategorization Features
• VFORM
• SUBCAT
• PFORM
• Binary features: +INV, or -INV
• Morphological Analysis
• Standard "conjugation" of English verbs
  • 3s suffix "-s"
  • Past tense suffix "ed"
  • Present participle "ing"
• Rules for verbs and nouns
• A simple lexicon with features

Readings

Sections 4.1-4.3

Assignment 5 p 78 #8, Implement the CFG in p76-77 #5 in prolog, p 79 #11 a, p 118 #1