Showing papers on "Indexed language published in 1993"
21 Apr 1993
TL;DR: The grammar-formalism generating the new class - the DI-grammars - cover unbound dependencies in a rather natural way and can equivalently be characterized by a special type of automata - DI-automata.
Abstract: 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.
11 citations
22 Jun 1993
TL;DR: It will be shown that using variables in lexical categories can increase the weak generative capacity of CCGs beyond the class of grammars listed above.
Abstract: Combinatory Categorial Grammars, CCGs, (Steedman 1985) have been shown by Weir and Joshi (1988) to generate the same class of languages as Tree-Adjoining Grammars (TAG), Head Grammars (HG), and Linear Indexed Grammars (LIG). In this paper, I will discuss the effect of using variables in lexical category assignments in CCGs. It will be shown that using variables in lexical categories can increase the weak generative capacity of CCGs beyond the class of grammars listed above.
10 citations