English

Scott Ranks of Classifications of the Admissibility Equivalence Relation

Logic 2017-12-05 v1

Abstract

Let L\mathscr{L} be a recursive language. Let S(L)S(\mathscr{L}) be the set of L\mathscr{L}-structures with domain ω\omega. Let Φ:ω2S(L)\Phi : {}^\omega 2 \rightarrow S(\mathscr{L}) be a Δ11\Delta_1^1 function with the property that for all x,yω2x,y \in {}^\omega 2, ω1x=ω1y\omega_1^x = \omega_1^y if and only if Φ(x)LΦ(y)\Phi(x) \approx_{\mathscr{L}} \Phi(y). Then there is some xω2x \in {}^\omega 2 so that SR(Φ(x))=ω1x+1\mathrm{SR}(\Phi(x)) = \omega_1^x + 1.

Keywords

Cite

@article{arxiv.1712.00847,
  title  = {Scott Ranks of Classifications of the Admissibility Equivalence Relation},
  author = {William Chan and Matthew Harrison-Trainor and Andrew Marks},
  journal= {arXiv preprint arXiv:1712.00847},
  year   = {2017}
}