On Friday, June 21, 2013 6:58:37 AM UTC-7, agapi...@aol.com wrote: > > > > Thanks. Is B, in fact, the power set of R? If not, what elements of the power set would be missing from B? > > > https://en.wikipedia.org/wiki/Borel_set#Non-Borel_sets > > > > Thanks for the link.