Properties of substitutions and unifications
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Handbook of theoretical computer science (vol. B)
Handbook of formal languages, vol. 3
Languages, automata, and logic
Handbook of formal languages, vol. 3
The Kleene-Schützenberger theorem for formal power series in partially commuting variables
Information and Computation
Automata, Languages, and Machines
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Syntax-Directed Semantics: Formal Models Based on Tree Transducers
Syntax-Directed Semantics: Formal Models Based on Tree Transducers
CSL '02 Proceedings of the 16th International Workshop and 11th Annual Conference of the EACSL on Computer Science Logic
An Axiomatization of Regular Forests in the Language of Algebraic Theories with Iteration
FCT '81 Proceedings of the 1981 International FCT-Conference on Fundamentals of Computation Theory
A Kleene Theorem for Weighted Tree Automata
Theory of Computing Systems
Algebraic recognizability of regular tree languages
Theoretical Computer Science - The art of theory
On the minimization of XML Schemas and tree automata for unranked trees
Journal of Computer and System Sciences
CSL'07/EACSL'07 Proceedings of the 21st international conference, and Proceedings of the 16th annuall conference on Computer Science Logic
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This paper proposes an alternative approach to the standard notion of rational (or regular) expression for tree languages. The main difference is that in the new notion we have only one concatenation operation and only one star-operation, instead of many different ones. This is achieved by considering forests instead of trees over a ranked alphabet, or, algebraicly speaking, by considering cartesian categories instead of term-algebras. The main result is that in the free cartesian category the rational languages and the recognizable languages coincide. For the construction of the rational expression for a recognizable language it is not necessary to extend the alphabet. We only use operations that can be defined with the algebraic structure provided by cartesian categories.