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Zero sharp (talk | contribs) added redirect to 'get the red out' w/ links to h.arith. heirarchy |
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I've seen redlinks to 'hyperarithmetical heirachy' many places, and just recently noticed [[hyperarithmetical theory]] so I've created a redirect for now. It's possible that one or the other will need to be renamed in the future, but I figured this was a cheap way to get rid of a lot of dead links at least for now. --- all assuming that 'hyperarithmetical theory' is talking about the same thing... here's hoping!
[[User:Zero sharp|Zero sharp]] 20:46, 30 August 2007 (UTC)
== Removed sentence ==
"Note that it rarely makes sense to speak of a <math>\Delta^1_n</math> ''formula''; the first quantifier of a formula is either existential or universal."
Well, not really, the first quantifier of the normalized form, but not of the formula. As we just demonstrated any formula in <math>\Pi^1_n</math> or <math>\Sigma^1_n</math> is in <math>\Delta^1_m</math> for all m>n. ''[[User:Rich Farmbrough|Rich]] [[User talk:Rich Farmbrough|Farmbrough]]'', 16:23, 14 December 2009 (UTC).
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