The breadth of constructibility degrees and definable Sierpiński’s coverings
Fundamenta Mathematicae
MSC: Primary 03E15; Secondary 03E45
DOI: 10.4064/fm240819-27-11
Published online: 20 May 2026
Abstract
Generalizing a result of Törnquist and Weiss, we study the connection between the existence of $ \varSigma _2^1 $ Sierpiński’s coverings of $\mathbb R ^n$, and a cardinal invariant of the upper semi-lattice of constructibility degrees known as breadth.
