Model-theoretic grammars, also known as constraint-based grammars, contrast with
generative grammar
Generative grammar, or generativism , is a linguistic theory that regards linguistics as the study of a hypothesised innate grammatical structure. It is a biological or biologistic modification of earlier structuralist theories of linguistic ...
s in the way they define sets of sentences: they state constraints on syntactic structure rather than providing operations for generating syntactic objects.
A generative grammar provides a set of operations such as rewriting, insertion, deletion, movement, or combination, and is interpreted as a definition of the set of all and only the objects that these operations are capable of producing through iterative application. A model-theoretic grammar simply states a set of conditions that an object must meet, and can be regarded as defining the set of all and only the structures of a certain sort that satisfy all of the constraints.
The approach applies the mathematical techniques of
model theory
In mathematical logic, model theory is the study of the relationship between formal theories (a collection of sentences in a formal language expressing statements about a mathematical structure), and their models (those structures in which the ...
to the task of syntactic description: a grammar is a
theory
A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may ...
in the logician's sense (a consistent set of statements) and the well-formed structures are the
models that satisfy the theory.
Examples of model-theoretic grammars
The following is a sample of grammars falling under the model-theoretic umbrella:
* the non-procedural variant of
Transformational grammar (TG) of
George Lakoff
George Philip Lakoff (; born May 24, 1941) is an American cognitive linguist and philosopher, best known for his thesis that people's lives are significantly influenced by the conceptual metaphors they use to explain complex phenomena.
The co ...
, that formulates constraints on potential tree sequences
* Johnson and Postal's formalization of
Relational grammar (RG) (1980),
Generalized phrase structure grammar (GPSG) in the variants developed by Gazdar et al. (1988), Blackburn et al. (1993) and Rogers (199