Then, it can be seen that if we sample uniformly from (w, c) ∈ Ω and c ∈ C \ {c}, then j(w, c, c which does not contain any expensive summations and is an unbiased estimator of (13), i.e., E [j(w, c, c )] = J (U, V, Ξ).
one can optimize ξ w,c exactly by using (12).