Symmetric Gaussian Problem
Determine, for fixed 0 ≤ ρ, μ, ν ≤ 1 and centrally symmetric A ⊆ R^n of Gaussian measure μ and B ⊆ R^n of Gaussian measure ν, the minimal possible value of Pr[X ∈ A, Y ∈ B] when (X, Y) are ρ-correlated n-dimensional Gaussians.
References
A reasonable conjecture is that the minimum occurs when A is a centered ball and B is the complement of a centered ball.
— Open Problems in Analysis of Boolean Functions
(1204.6447 - O'Donnell, 2012) in Main matter, problem “Symmetric Gaussian Problem,” remarks, third bullet