Fσ set: Revision history

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For any version listed below, click on its date to view it. For more help, see Help:Page history and Help:Edit summary. (cur) = difference from current version, (prev) = difference from preceding version, m = minor edit, → = section edit, ← = automatic edit summary

1 December 2025

  • curprev 00:1900:19, 1 December 2025 imported>Nickwgo m 2,840 bytes +100 Noted that a countable union of F-sigma sets need only be F-sigma if we assume Countable Choice. I'd love to add a citation for this but I legitimately can't find one that's publicly available (although for a source, see Set Theory Third Millennium Edition (2003) by Thomas Jech, page 50). It's true for precisely the same reason that a countable union of countable sets being countable requires Countable Choice.

6 January 2024

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