English

Characterization of $\ell_p$-like and $c_0$-like equivalence relations

Logic 2010-06-24 v1 General Topology

Abstract

Let XX be a Polish space, dd a pseudo-metric on XX. If {(u,v):d(u,v)<δ}\{(u,v):d(u,v)<\delta\} is Π11{\bf\Pi}^1_1 for each δ>0\delta>0, we show that either (X,d)(X,d) is separable or there are δ>0\delta>0 and a perfect set CXC\subseteq X such that d(u,v)δd(u,v)\ge\delta for distinct u,vCu,v\in C. Granting this dichotomy, we characterize the positions of p\ell_p-like and c0c_0-like equivalence relations in the Borel reducibility hierarchy.

Keywords

Cite

@article{arxiv.1006.4405,
  title  = {Characterization of $\ell_p$-like and $c_0$-like equivalence relations},
  author = {Longyun Ding},
  journal= {arXiv preprint arXiv:1006.4405},
  year   = {2010}
}

Comments

8 pages, submitted