Optimized affine shift of concave utility (source code)

= Optimized affine shift of concave utility

Let $\mathcal X$ be a vector space of random variables and suppose
$$
F(y)=\sup_{X\in\mathcal X}\mathbb E[U(X+y)]
$$
has an optimizer for every $y$. If $U$ is increasing and concave, then $F$ is increasing and concave. For concavity, combine optimizers at two values using the same convex coefficient as the values themselves.