We prove there is a countable dense homogeneous subspace of ℝ of size ℵ₁. The proof involves an absoluteness argument using an extension of the logic obtained by adding predicates for Borel sets.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-fm186-1-5,
author = {Ilijas Farah and Michael Hru\v s\'ak and Carlos Azarel Mart\'\i nez Ranero},
title = {A countable dense homogeneous set of reals of size 1},
journal = {Fundamenta Mathematicae},
volume = {185},
year = {2005},
pages = {71-77},
zbl = {1083.54020},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-fm186-1-5}
}
Ilijas Farah; Michael Hrušák; Carlos Azarel Martínez Ranero. A countable dense homogeneous set of reals of size ℵ₁. Fundamenta Mathematicae, Tome 185 (2005) pp. 71-77. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-fm186-1-5/