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The term "analytical" refers exclusively to the lightface concept, whereas "projective" is a boldface notion. Therefore "projective set" should not redirect here. I'm planning a [[pointclass]] page where it might redirect instead. Also "analytic" and "co-analytic", which are boldface notions, should be removed from this page. --[[User:Trovatore|Trovatore]] 7 July 2005 20:35 (UTC)
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The other major problem with this page is the conflation of formulas and sets. Consider for example the following passage:
: A <math>\Sigma^1_1</math> formula is a formula of the form <math>\exists X \phi</math>, where ''X'' is now a [[Mathematical_relation | predicate]] and <math>\phi \in \Sigma^1_0</math>, while a <math>\Sigma^1_1</math> set is a set of the form
: <math>\{x : (\exists y \in S)\ R(x,y) \}</math>,
: where ''S'' is Borel and ''R'' is a relation.
First, the definition is incorrect, because no restriction is placed on the definability of ''R''. But the problem that more exemplifies the difficulty with the page as a whole is that nothing is said about the underlying Polish space. --[[User:Trovatore|Trovatore]] 7 July 2005 20:48 (UTC)
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