Showing papers on "Indexed language published in 1995"
Posted Content•
TL;DR: This article showed that a sufficiently long word in an indexed language can be written as a product of a uniformly bounded number of terms in such a way that some proper subproduct belongs to the language.
Abstract: This article presents a combinatorial result on indexed languages which was inspired by an attempt to understand the structure of groups with indexed language word problem. We show that a sufficiently long word in an indexed language can be written as a product of a uniformly bounded number of terms in such a way that some proper subproduct belongs to the language.
32 citations
Proceedings Article•
01 Jan 1995
16 citations
TL;DR: A generalization of the context-free LR(k)-notion is presented, which characterizes for each language class in the hierarchy generated by coupled-context-free grammars — and therefore for TAGs, too — a subclass, which can be parsed in linear time.
2 citations
TL;DR: Terminally coded (TC) grammars are introduced, which generalize parenthesis Grammar in the sense that from each word ω generated by a TC grammar the authors can recover the unlabeled tree t underlying its derivation tree(s), and there is a length-preserving homomorphism that maps ω to an encoding of t.
Abstract: We introduce terminally coded (TC) grammars, which generalize parenthesis grammars in the sense that from each word ω generated by a TC grammar we can recover the unlabeled tree t underlying its derivation tree(s). More precisely, there is a length-preserving homomorphism that maps ω to an encoding of t. Basic properties of TC grammars are established. For backwards deterministic TC grammars we give a shift-reduce precedence parsing method without look-ahead, which implies that TC languages can be recognized in linear time. The class of TC languages contains all parenthesis languages, and is contained in the classes of simple precedence languages and NTS languages.
1 citations
Posted Content•
TL;DR: A class of unification grammars is defined that exactly describes the class of indexed languages.
Abstract: Indexed languages are interesting in computational linguistics because they are the least class of languages in the Chomsky hierarchy that has not been shown not to be adequate to describe the string set of natural language sentences. We here define a class of unification grammars that exactly describe the class of indexed languages.
1 citations