Paper: QPATR And Constraint Threading

ACL ID C90-3080
Title QPATR And Constraint Threading
Venue International Conference on Computational Linguistics
Session Main Conference
Year 1990

QPATR is an MS-DOS Arity/PROLOG implemen- tation of the PATR-II formalism for unification grammar. The fbnnalism has been extended to include the constraints of LFG as well as negation and disjunction, which are implemented with the disjunction and negation-as-failure of PROLOG itself. A technique of constraint threading is employed to collect negative and constraining conditions in PROLOG difference lists. The parser of QPATR uses a left-corner algorithm for context-free grammars and includes a facility for identifying new lexical items in input on the basis of contextual information.