• Media type: E-Article
  • Title: Tree-Automatic Well-Founded Trees
  • Contributor: Huschenbett, Martin [Author]; Kartzow, Alexander [Author]; Liu, Jiamou [Author]; Lohrey, Markus [Author]
  • Published: Digital Library Thüringen, 2013-08-05
  • Language: German
  • Keywords: hyperarithmetical hierarchy ; tree-automatic structures ; Klasse A ; well-founded trees ; ordinal rank ; ScholarlyArticle ; für Harvesting bereitgestellt ; isomorphism problem ; article
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  • Description: We investigate tree-automatic well-founded trees. Using Delhomme's decomposition technique for tree-automatic structures, we show that the (ordinal) rank of a tree-automatic well-founded tree is strictly below omega^omega. Moreover, we make a step towards proving that the ranks of tree-automatic well-founded partial orders are bounded by omega^omega^omega: we prove this bound for what we call upwards linear partial orders. As an application of our result, we show that the isomorphism problem for tree-automatic well-founded trees is complete for level Delta^0_{omega^omega} of the hyperarithmetical hierarchy with respect to Turing-reductions.
  • Access State: Open Access