Restricting logic grammars with government-binding theory
Computational Linguistics
Indexed Grammars—An Extension of Context-Free Grammars
Journal of the ACM (JACM)
Journal of the ACM (JACM)
Computational Linguistics
Characterizing structural descriptions produced by various grammatical formalisms
ACL '87 Proceedings of the 25th annual meeting on Association for Computational Linguistics
ACL '88 Proceedings of the 26th annual meeting on Association for Computational Linguistics
Tree adjoining and head wrapping
COLING '86 Proceedings of the 11th coference on Computational linguistics
Multiset-valued linear index grammars: imposing dominance constraints on derivations
ACL '94 Proceedings of the 32nd annual meeting on Association for Computational Linguistics
The copying power of well-nested multiple context-free grammars
LATA'10 Proceedings of the 4th international conference on Language and Automata Theory and Applications
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A new class of formal languages will be defined - the Distributed Index Languages (DI-languages). The grammar-formalism generating the new class - the DI-grammars - cover unbound dependencies in a rather natural way. The place of DI-languages in the Chomsky-hierarchy will be determined: Like Aho's indexed Languages, DI-languages represent a proper subclass of Type 1 (contextsensitive languages) and properly include Type 2 (context-free languages), but the DI-class is neither a subclass nor a superclass of Aho's indexed class. It will be shown that, apart from DI-grammars, DI-languages can equivalently be characterized by a special type of automata - DI-automata. Finally, the time complexity of the recognition-problem for an interesting subclass of DI-Grammars will approximately be determined.