Reals n-generic relative to some perfect tree

نویسنده

  • Bernard A. Anderson
چکیده

We say that a real X is n-generic relative to a perfect tree T if X is a path through T and for all Σn(T ) sets S, there exists a number k such that either X|k ∈ S or for all σ ∈ T extending X|k we have σ / ∈ S. A real X is n-generic relative to some perfect tree if there exists such a T . We first show that for every number n all but countably many reals are n-generic relative to some perfect tree. Second, we show that proving this statement requires ZFC− + “∃ infinitely many iterates of the power set of ω”. Third, we prove that every finite iterate of the hyperjump, O, is not 2-generic relative to any perfect tree and for every ordinal α below the least λ such that supβ<λ(βth admissible) = λ, the iterated hyperjump O is not 5-generic relative to any perfect tree. Finally, we demonstrate some necessary conditions for reals to be 1-generic relative to some perfect tree.

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عنوان ژورنال:
  • J. Symb. Log.

دوره 73  شماره 

صفحات  -

تاریخ انتشار 2008