“…We also mention though that the special case of optimal transportation is given by taking g(x, y, z) = c(x, y) − z, (1.3) where c is a cost function defined on a domain D in R n × R n so that = D × R, g x = c x , g z = −1, E x,y = c x,y and conditions A1 and A2 are equivalent to those in [11,19]. Note that here we follow the same sign convention as in [15,20] so that our cost functions are the negatives of those usually considered. We remark also that the case when Y is independent of u is equivalent to the optimal transportation case.…”