How can we recognize potentially ${\bfΠ}^0_ξ$ subsets of the plane?

Dominique Lecomte

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arXiv · 0905.4875

How can we recognize potentially ${\bfΠ}^0_ξ$ subsets of the plane?

Dominique Lecomte

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Abstract

Let $ξ\geq 1$ be a countable ordinal. We study the Borel subsets of the plane that can be made ${\bfΠ}^0_ξ$ by refining the Polish topology on the real line. These sets are called potentially ${\bfΠ}^0_ξ$. We give a Hurewicz-like test to recognize potentially ${\bfΠ}^0_ξ$ sets.

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Dominique Lecomte. 2009-05-29. How can we recognize potentially ${\bfΠ}^0_ξ$ subsets of the plane?. https://arxiv.org/abs/0905.4875

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