Topic
Indexed language
About: Indexed language is a research topic. Over the lifetime, 334 publications have been published within this topic receiving 11000 citations.
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TL;DR: A modified language generating mechanism for NLC grammars is introduced, and the resulting class of graph languages is compared to the class of NLC languages.
3 citations
14 Jun 1972
TL;DR: In this article, it was shown that a grammar such that in each noncontext-free rule of G, the right side contains a string of terminals longer than any terminal string appearing between two nonterminals in the left side is context-free.
Abstract: If G is a grammar such that in each noncontext-free rule of G, the right side contains a string of terminals longer than any terminal string appearing between two nonterminals in the left side; then the language generated by G is context-free Six previous results follow as simple corollaries of this theorem
3 citations
3 citations
TL;DR: A polynomial algorithm for parsing with SIGs is given that is a rather straightforward extension of the Earley algorithm for Parsing with context-free grammars.
Abstract: This article defines the grammar class of sequentially indexed grammars (SIGs) that results of a change in the index stack handling mechanism of indexed grammars (Aho, 1968, Journal of the ACM, 15, 647–671; 1969, Journal of the ACM, 16, 383–406). SIGs are different from linear indexed grammars (Gazdar, 1988, Natural Language, Parsing and Linguistic, Theories, pp. 69–94) (the rule format is simpler) and they generate a strictly larger language class. We give a polynomial algorithm for parsing with SIGs that is a rather straightforward extension of the Earley algorithm for parsing with context-free grammars. SIGs are attractive because of the simple rule format, the natural correspondence between indices and traces, and the perspicuity of the parsing scheme.
3 citations
Journal Article•
3 citations