Colored nested words

Rajeev Alur, Dana Fisman

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

5 Scopus citations


Nested words allow modeling of linear and hierarchical structure in data, and nested word automata are special kinds of pushdown automata whose push/pop actions are directed by the hierarchical structure in the input nested word. The resulting class of regular languages of nested words has many appealing theoretical properties, and has found many applications, including model checking of procedural programs. In the nested word model, the hierarchical matching of open- and close- tags must be properly nested, and this is not the case, for instance, in program executions in presence of exceptions. This limitation of nested words narrows its model checking applications to programs with no exceptions. We introduce the model of colored nested words which allows such hierarchical structures with mismatches. We say that a language of colored nested words is regular if the language obtained by inserting the missing closing tags is a well-colored regular language of nested words. We define an automata model that accepts regular languages of colored nested words. These automata can execute restricted forms of ε-pop transitions. We provide an equivalent grammar characterization and show that the class of regular languages of colored nested words has the same appealing closure and decidability properties as nested words, thus removing the restriction of programs to be exception-free in order to be amenable for model checking, via the nested words paradigm.

Original languageEnglish
Title of host publicationLanguage and Automata Theory and Applications - 10th International Conference, LATA 2016, Proceedings
EditorsBianca Truthe, Jan Janoušek, Adrian-Horia Dediu, Carlos Martín-Vide
PublisherSpringer Verlag
Number of pages13
ISBN (Print)9783319299990
StatePublished - 1 Jan 2016
Externally publishedYes
Event10th International Conference on Language and Automata Theory and Applications, LATA 2016 - Prague, Czech Republic
Duration: 14 Mar 201618 Mar 2016

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference10th International Conference on Language and Automata Theory and Applications, LATA 2016
Country/TerritoryCzech Republic

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science (all)


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