Regular tree languages, cardinality predicates, and addition-invariant FO
- This paper considers the logic FOcard, i.e., first-order logic with cardinality predicates that can specify the size of a structure modulo some number. We study the expressive power of FOcard on the class of languages of ranked, finite, labelled trees with successor relations. Our first main result characterises the class of FOcard-definable tree languages in terms of algebraic closure properties of the tree languages. As it can be effectively checked whether the language of a given tree automaton satisfies these closure properties, we obtain a decidable characterisation of the class of regular tree languages definable in FOcard. Our second main result considers first-order logic with unary relations, successor relations, and two additional designated symbols < and + that must be interpreted as a linear order and its associated addition. Such a formula is called addition-invariant if, for each fixed interpretation of the unary relations and successor relations, its result is independent of the particular interpretation of < and +. We show that the FOcard-definable tree languages are exactly the regular tree languages definable in addition-invariant first-order logic. Our proof techniques involve tools from algebraic automata theory, reasoning with locality arguments, and the use of logical interpretations. We combine and extend methods developed by Benedikt and Segoufin (ACM ToCL, 2009) and Schweikardt and Segoufin (LICS, 2010).
Author: | Frederik Harwath, Nicole Schweikardt |
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URN: | urn:nbn:de:hebis:30:3-237188 |
DOI: | https://doi.org/10.4230/LIPIcs.STACS.2012.489 |
ISBN: | 978-3-939897-35-4 |
ISSN: | 1868-8969 |
Parent Title (English): | Christoph Dürr ; Thomas Wilke (Hrsg.): 29th International Symposium on Theoretical Aspects of Computer Science (STACS 2012) = Leibniz international proceedings in informatics, 14.2012 |
Publisher: | Schloss Dagstuhl - Leibniz-Zentrum für Informatik GmbH |
Place of publication: | Wadern |
Editor: | Christoph Dürr, Thomas Wilke |
Document Type: | Conference Proceeding |
Language: | English |
Date of Publication (online): | 2011/12/23 |
Year of first Publication: | 2012 |
Publishing Institution: | Universitätsbibliothek Johann Christian Senckenberg |
Contributing Corporation: | International Symposium on Theoretical Aspects of Computer Science (29. : 2012 : Paris) |
Release Date: | 2011/12/23 |
Tag: | addition-invariant first-order logic; algebraic closure properties; decidable characterisations; logical interpretations; regular tree languages |
Page Number: | 12 |
First Page: | 489 |
Last Page: | 500 |
Note: | © Frederik Harwath and Nicole Schweikardt; licensed under Creative Commons License NC-ND |
HeBIS-PPN: | 301732442 |
Institutes: | Informatik und Mathematik / Informatik |
Dewey Decimal Classification: | 0 Informatik, Informationswissenschaft, allgemeine Werke / 00 Informatik, Wissen, Systeme / 000 Informatik, Informationswissenschaft, allgemeine Werke |
Sammlungen: | Universitätspublikationen |
Licence (German): | Creative Commons - Namensnennung-Nicht kommerziell-Keine Bearbeitung 3.0 |