This condition is equivalent to stochastic mixability as well as the pseudoprobability convexity (PPC) condition, both defined by Van Erven et al. (2015). To be precise, for stochastic mixability, in Definition 4.1 of Van Erven et al. (2015), take their Fd and F both equal to our F , their P equal to {P}, and ψ(f) = f∗; then strong stochastic mixability holds. Likewise, for the PPC condition, i...