Some 2-point sets
Volume 208 / 2010
Fundamenta Mathematicae 208 (2010), 87-91
MSC: Primary 03E05; Secondary 03C64.
DOI: 10.4064/fm208-1-6
Abstract
Chad, Knight & Suabedissen [Fund. Math. 203 (2009)] recently proved, assuming CH, that there is a $2$-point set included in the union of countably many concentric circles. This result is obtained here without any additional set-theoretic hypotheses.
