Indexed language

About: Indexed language is a research topic. Over the lifetime, 334 publications have been published within this topic receiving 11000 citations.

Checking Automata and One-Way Stack Languages (Extended Abstract)

Abstract: A checking automaton is equivalent to a one-way nonerasing stack automaton which, once it enters its stack, never again writes on its stack. The checking automaton languages (cal) form a full AFL closed under substitution. If L ⊆ a* is an infinite cal, then L contains an infinite regular set. Consequently, there are one-way nonerasing stack languages (such as (an2|n≥1|)) which are not cal. Let L be the family of one-way stack languages and let L1 be a subAFL of L. L is closed under substitution into L1 if and only if L1 is contained in the family of context-free languages. L is closed under substitution by L1 if and only if L1 is a family of cal. Hence, the one-way stack languages are not closed under substitution. The one-way nested stack languages properly include the stack languages. The family of quasi-real-time one-way stack languages is not closed under substitution by cal. Thus the quasi-real-time one-way stack languages are not a full AFL but are a proper subAFL of the one-way stack languages. Let LN be the family of one-way nonerasing stack languages, and let L1 be a subAFL. Then LN is closed under substitution into L1 if and only if L1 is a family of regular sets. Hence LN is a proper subfamily of L.

Synchronization of Models of Rich Languages with Triple Graph Grammars

Abstract: We report our experience of using Triple Graph Grammars (TGG) to synchronize models of the rich and complex Architecture Analysis and Design Language (AADL), an aerospace standard of the Society of Automotive Engineers. A synchronization layer has been developed between the OSATE (Open Source AADL Tool Environment) textual editor and the Adele graphical editor in order to improve their integration. Adele has been designed to support editing AADL models in a way that does not necessarily follow the structure of the language, but is adapted to the way designers think. For this reason, it operates on a different meta-model than OSATE. As a result, changes on the graphical model must be propagated automatically to the textual model to ensure consistency of the models. Since Adele does not cover the complete AADL language, this must be done without re-instantiation of the objects to avoid losing the information not represented in the graphical part. The TGG language implemented in the MoTE tool has been used to synchronize the tools. Our results provide a validation of the TGG approach for synchronizing models of large meta-models, but also show that model synchronization remains a challenging task, since several improvements of the TGG language and its tool were required to succeed.

On using semi-Dyck sets to analyse coupled-context-free languages

Abstract: Coupled-Context-Free Grammars are a natural generalization of context-free grammars obtained by combining nonterminals to corresponding parentheses which can only be substituted simultaneously. Refering to their generative capacity we obtain an infinite hierarchy of languages that comprises the context-free ones as the first and all those generated by Tree Adjoining Grammars (TAGs) as the second element. The latter is important because today, TAGs are commonly used to model the syntax of natural languages. Here, we present a completely new approach to analyse this language hierarchy. It solves the word problem for the class of languages generated by TAGs in time O(n 6), n length of the input, by reducing it to the analysis of sequences of parentheses. (This research has been supported by a Graduiertenkolleg-fellowship of the Deutsche Forschungs-gemeinschaft and by the ESPRIT Basic Research Action No. 6317 (ASMICS2).)