A Machine-Oriented Logic Based on the Resolution Principle
Journal of the ACM (JACM)
ACL '84 Proceedings of the 10th International Conference on Computational Linguistics and 22nd annual meeting on Association for Computational Linguistics
Functional Unification Grammar: a formalism for machine translation
ACL '84 Proceedings of the 10th International Conference on Computational Linguistics and 22nd annual meeting on Association for Computational Linguistics
Category cooccurrence restrictions and the elimination of metarules
COLING '86 Proceedings of the 11th coference on Computational linguistics
Parsing with Category Coocurrence Restrictions
COLING '88 Proceedings of the 12th conference on Computational linguistics - Volume 1
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Recent investigations show a remarkable convergence among contemporary unification-based formalisms for syntactic description. This convergence is now itself becoming an object of study, and there is an increasing recognition of the need for explicit characterizations of the properties that relate and distinguish similar grammar formalisms. The paper proposes a series of changes in the formalism of Generalized Phrase Structure Grammar that throw light on its relation to Functional Unification Grammar.The essential contribution is a generalization of cooccurrence restrictions, which become the principal and unifying device of GPSG. Introducing Category Cooccurrence Restrictions (CCRs) for local trees (in analogy to Feature Cooccurrence Restrictions for categories) provides a genuine gain in expressiveness for the formalism. Other devices, such as Feature Instantiation principles and Linear Precedence Statements can be regarded as special cases of CCRs. The proposals lead to a modified notion of unification itself.