Talk:Kleene's O
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Unique or not?
[edit]To Logicnazi (talk · contribs): You keep saying that the notations in Kleene's O are unique. That is, you appear to be saying that each recursive ordinal corresponds to only one member of Kleene's O. This contradicts what I learned when I studied the subject. And it contradicts the fact that Kleene's O is not effective. Please justify this assertion or stop making it! JRSpriggs (talk) 20:56, 2 August 2008 (UTC)
Claim about paths in O needs a reference
[edit]A question about a result claimed on this page came up on Math Overflow. (See "http://mathoverflow.net/questions/71584/hyperarithmetic-statements-decidable-by-induction-up-to-a-recursive-ordinal/72322#72322".) There needs to be either a reference or more complete proof of the second sentence in "There exist $\aleph_0$ paths through $\mathcal{O}$ which are $\Pi^1_1$. Given a progression of recursively enumerable theories based on iterating Uniform Reflection, each such path is incomplete with respect to the set of true $\Pi^0_1$ sentences."Mtnmath (talk) 17:04, 11 August 2011 (UTC)