# Unambiguous Tree Languages Are Topologically Harder Than Deterministic Ones

@inproceedings{Hummel2012UnambiguousTL,
title={Unambiguous Tree Languages Are Topologically Harder Than Deterministic Ones},
author={Szczepan Hummel},
booktitle={GandALF},
year={2012}
}
• S. Hummel
• Published in GandALF 7 October 2012
• Computer Science
The paper gives an example of a tree language G that is recognised by an unambiguous parity automaton and is analytic-complete as a set in Cantor space. This already shows that the unambiguous languages are topologically more complex than the deterministic ones, that are all coanalytic. Using set G as a building block we construct an unambiguous language that is topologically harder than any countable boolean combination of analytic and coanalytic sets. In particular the language is harder…

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