A note on complex unions of subsets of the real line
Solecki has shown that a broad natural class of ideals of compact sets can be represented through the ideal of nowhere dense subsets of a closed subset of the hyperspace of compact sets. In this note we show that the closed subset in this representation can be taken to be closed upwards.
We show that in every Polish, abelian, non-locally compact group G there exist non-Haar null sets A and B such that the set {g ∈ G; (g+A) ∩ B is non-Haar null} is empty. This answers a question posed by Christensen.
We prove that for λ ∈ [0,1] and A, B two Borel sets in with A convex, , where is the canonical gaussian measure in and is the inverse of the gaussian distribution function.