Talk:Borel determinacy theorem

Friedman's theorem
"'Friedman's theorem of 1971 showed that there is no countable ordinal &delta; such that V&delta; satisfies Borel determinacy.'"

This doesn't seem right; isn't Borel determinacy a statement about the existence or nonexistence of sets living in V&omega;+&omega;, so that if you start with a model of ZFC then V&delta; will satisfy Borel determinacy for any &delta;&ge;&omega;+&omega;? I looked up Friedman's theorem, and it seems that what he actually does is construct a different model L&omega;+&omega;, related to the constructible universe, which satisfies Z but not Borel determinacy.

Michael Shulman (talk) 21:06, 8 March 2008 (UTC)


 * ✅ Correct, the statement in the article has since been fixed. AxelBoldt (talk) 16:36, 28 January 2022 (UTC)