Constraint based grammar

Constraint-based grammars can perhaps be best understood in contrast to generative grammars. A generative grammar lists all the transformations, merges, movements, and deletions that can result in all well-formed sentences, while constraint-based grammars, take the opposite approach, allowing anything that is not otherwise constrained. "The grammar is nothing but a set of contraints that structures are required to satisfy in order to be considered well-formed." "A constrain-based grammar is more like a data base or a knowledge representation system than it is like a collection of algorithms."

Examples of such grammars include