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
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).
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Metadaten
Author:Frederik Harwath, Nicole Schweikardt
URN:urn:nbn:de:hebis:30:3-237188
DOI:http://dx.doi.org/10.4230/LIPIcs.STACS.2012.489
ISBN:978-3-939897-35-4
Parent Title (English):29th International Symposium on Theoretical Aspects of Computer Science (STACS 2012)
Publisher:Schloss Dagstuhl - Leibniz-Zentrum für Informatik GmbH
Place of publication:Wadern
Document Type:Conference Proceeding
Language:English
Date of Publication (online):2012/02/24
Date of first Publication:2012/02/24
Publishing Institution:Univ.-Bibliothek Frankfurt am Main
Release Date:2011/12/23
Tag:addition-invariant first-order logic; algebraic closure properties; decidable characterisations; logical interpretations; regular tree languages
Pagenumber:12
First Page:489
Last Page:500
HeBIS PPN:301732442
Institutes:Informatik
Dewey Decimal Classification:004 Datenverarbeitung; Informatik
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung-Nicht kommerziell-Keine Bearbeitung 3.0

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