Talk:Positive set theory

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 Field: Foundations, logic, and set theory


The previous version of this article contained some errors. The notation given for closure was the usual notation for a one-element set. The class of well-founded sets is not a set, and it is the (proper) class of well-founded sets which is the domain of the interpretation of ZFC, not the class of sets with complements.

Randall Holmes 01:37, 15 December 2005 (UTC)

Thanks Randall! Glad to have you around; I was a pretty poor approximation of an "expert" on this topic, though hopefully better than nobody ;) -- Megacz 19:24, 15 December 2005 (UTC)

Cartesian Closure[edit]

I am quite curious to know if there are proofs that the sets of GPK+\infty do or do not form a carteisan closed category (those of NF do not: New_Foundations#Cartesian_Closure). Has any work on this been published? Any hunches? AshtonBenson (talk) 06:52, 7 July 2009 (UTC)

Positive Formula[edit]

I arrived here looking for a definition and exlpanation of Positive Formula. (The Lemma Positive formula redirects to here). Could someone who knows about this please add a characterization of positive formulae? -- (talk) 12:08, 19 October 2011 (UTC)