Lexical Functional Grammar

Lexical functional grammar (LFG) is a grammar framework in theoretical linguistics with constraint-based and generative varieties. It is a type of phrase structure grammar, as opposed to a dependency grammar. The development of the theory was initiated by Joan Bresnan and Ronald Kaplan in the 1970s, in reaction to the direction of research that transformational grammar was taking. It mainly focuses on syntax, including its relation with morphology and semantics. There has been little LFG work on phonology (although ideas from optimality theory have recently been popular in LFG research).

LFG views language as being made up of multiple dimensions of structure. Each of these dimensions is represented as a distinct structure with its own rules, concepts, and form. The primary structures that have figured in LFG research are:

For example, in the sentence The old woman eats the falafel, the c-structure analysis is that this is a sentence which is made up of two pieces, a noun phrase (NP) and a verb phrase (VP). The VP is itself made up of two pieces, a verb (V) and another NP. The NPs are also analyzed into their parts. Finally, the bottom of the structure is composed of the words out of which the sentence is constructed. The f-structure analysis, on the other hand, treats the sentence as being composed of attributes, which include features such as number and tense or functional units such as subject, predicate, or object.

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