On Deciding Topological Classes of Deterministic Tree Languages

Abstract. It has been proved by Niwi´nski and Walukiewicz that a deterministic tree language is either Π1 1 -complete or it is on the level Π0 3 of the Borel hierarchy, and that it can be decided effectively which of the two takes place. In this paper we show how to decide if the language recognized by a given deterministic tree automaton is on the Π0 2 , the Σ0 2 , or the Σ0 3 level. Together with the previous results it gives a procedure calculating the exact position of a deterministic tree language in the topological hierarchy.

• Type: Conference
• Year: 2005
• Where: CSL
• Authors: Filip Murlak
• Keywords: CSL 2005, Deterministic Tree, Deterministic Tree Automaton, Deterministic Tree Language