“…If a distribution is spanned by a unit vector field N , i.e., N, N = N ∈ {−1, 1}, then S mix = N Ric N,N , where Ric N,N is the Ricci curvature in the N -direction. If dim M = 2 and dim D = 1, then obviously 2S mix = S. If T = 0 then S mix reduces to the mixed scalar curvature S mix of ∇, see (10), which can be defined as a sum of sectional curvatures of planes that non-trivially intersect with both of the distributions. Investigation of S mix led to multiple results regarding the existence of foliations and submersions with interesting geometry, e.g., integral formulas and splitting results, curvature prescribing and variational problems, see survey [23].…”