Showing papers on "Indexed language published in 2002"
TL;DR: It is shown that there exists a unique minimal balanced grammar equivalent to a given one and balanced languages are characterized through a property of their syntactic congruence.
Abstract: Balanced grammars are a generalization of parenthesis grammars in two directions. First, several kind of parentheses are allowed. Next, the set of right-hand sides of productions may be an infinite regular language. XML-grammars are a special kind of balanced grammars. This paper studies balanced grammars and their languages. It is shown that there exists a unique minimal balanced grammar equivalent to a given one. Next, balanced languages are characterized through a property of their syntactic congruence. Finally, we show how this characterization is related to previous work of McNaughton and Knuth on parenthesis languages.
45 citations
TL;DR: A pumping lemma for random context languages of finite index is proved that generalizes and refines the existing one, and it is shown that these Grammars are strictly weaker than the non-erasing random context grammars.
30 citations
TL;DR: The delta of a language L consists of the yields of trees of which all paths are in L, which are the deltas of the regular languages and the context-free languages.
Abstract: The delta of a language L consists of the yields of trees of which all paths are in L. The context-free languages are the deltas of the regular languages. The indexed languages are the deltas of the deterministic context-free languages. In general, the nondeterministic (n + 1)-iterated pushdown languages are the deltas of the deterministic n- iterated pushdown languages. The recursively enumerable languages are the deltas of the context-free languages. The delta of a string relation R consists of the yields of trees of which all paths are in the R-image of one string. The ET0L languages are the deltas of the relations recognized by deterministic two-tape finite automata. The recursively enumerable languages are the deltas of the finite state transductions.
2 citations
01 Jan 2002
TL;DR: A full operational framework is provided, that allows us to transform tree grammars into Prolog programs (as it already exists for word Grammars with DCG) whose goal is to recognize terms of the corresponding language.
Abstract: Tree languages are powerful tools for the representation and schematization of infinite sets of terms for various purposes (unification theory, verification and specification ...). In order to extend the regular tree language framework, more complex formalisms have been developed. In this paper, we focus on Tree Synchronized Grammars and Primal Grammars which introduce specific control structures to represent non regular sets of terms. We propose a common unified framework in order to achieve the membership test for these particular languages. Thanks to a proof system, we provide a full operational framework, that allows us to transform tree grammars into Prolog programs (as it already exists for word grammars with DCG) whose goal is to recognize terms of the corresponding language.