How can we recognize potentially ${\bfΠ}^0_ξ$ subsets of the plane?
英文摘要：
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.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
