LFG

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What is Lexical-Functional Grammar?

Lexical Functional Grammar is a theory of grammar -- that is, in general terms, a theory of:

  • syntax (roughly, how words can be combined together to make larger phrases, such as sentences),
  • morphology (how morphemes --- parts of words, such as the parts of writers, namely the verb write, the `agentive affix' er and the plural marker +s --- can be combined to make up words),
  • semantics (how and why various words and combinations of words mean what they mean), and
  • pragmatics (how expressions are used to transmit information).

In addition, grammar is often taken to include phonology (the study of the sound systems of human languages), but LFG has relatively little to say about this.

In LFG, there are two fundamental levels of syntactic representation: constituent structure (c-structure) and functional structure (f-structure).

  • C-structures have the form of context-free phrase structure trees.
  • F-structures are sets of pairs of attributes and values; attributes may be features, such as tense and gender, or functions, such as subject and object.

The name of the theory emphasizes an important difference between LFG and the Chomskyan tradition from which it developed: many phenomena are thought to be more naturally analysed in terms of grammatical functions as represented in the lexicon or in f-structure, rather than on the level of phrase structure. An example is the alternation between active and passive, which rather than being treated as a transformation, is handled in the lexicon. Grammatical functions are not derived from phrase structure configurations, but are represented at the parallel level of functional structure.

[Victoria Rosen, University of Bergen, with additions by Ron Kaplan,Joan Bresnan, and Doug Arnold]

Some of the messages on the LFG-list discuss quite basic ideas of LFG.

See also:


Current Development Efforts in LFG

The following are some of the projects currently involved in developing grammars or systems using LFG.

  • The LFG Pargram Project(s):
  • The LFG Pargram Project
  • The LFG pargram Project at Stuttgart in Germany
  • The LFG NorGRAM Project at Bergen in Norway
  • The LFG Urdu Pargram Project at Konstanz in Germany
  • The Indonesian Pargram Project at the ANU in Australia
  • Verb-initial Grammars Page
  • Researchers at Dublin City University are developing grammars and resources from treebanks.
  • See also, the Norwegian LOGON project.