13 Chart Parsing for Unification Grammars

So far, we've looked at pure context-free grammars in which categories are atoms. In contemporary computational linguistics however, most grammars are feature-based that is, they have categories that are feature terms (rather than atoms). In this section, we discuss first, how to implement feature-based grammars (also called, unification-based grammars as unification is the main operation used for comparing and combining categories) and second, how to implement a chart parser for such grammars.

• 13.1 Unification-based Grammars
  • 13.1.1 Feature Terms
  • 13.1.2 Path equations
  • 13.1.3 Organising the lexicon

• 13.2 Unification-based Parsing
  • 13.2.1 Structured.categories
  • 13.2.2 Is Context Free Grammar Enough?
  • 13.2.3 Rule Formats
  • 13.2.4 Chart Parsing
  • 13.2.5 A Simplistic Example

• 13.3 The Complete Package

• 13.4 Exercises