English

Generic Coding with Help and Amalgamation Failure

Logic 2021-04-08 v3

Abstract

We show that if MM is a countable transitive model of ZF and if a,ba,b are reals not in MM, then there is a GG generic over MM such that bL[a,G]b \in L[a,G]. We then present several applications such as the following: if JJ is any countable transitive model of ZFC and M⊈JM \not\subseteq J is another countable transitive model of ZFC of the same ordinal height α\alpha, then there is a forcing extension NN of JJ such that MNM \cup N is not included in any transitive model of ZFC of height α\alpha. Also, assuming 0#0^\# exists, letting SS be the set of reals generic over LL, although SS is disjoint from the Turing cone above 0#0^\#, we have that for any non-constructible real aa, {as:sS}\{ a \oplus s : s \in S \} is cofinal in the Turing degrees.

Keywords

Cite

@article{arxiv.1808.10304,
  title  = {Generic Coding with Help and Amalgamation Failure},
  author = {Sy-David Friedman and Dan Hathaway},
  journal= {arXiv preprint arXiv:1808.10304},
  year   = {2021}
}

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14 pages