please let me know, the assumptions over the Lagrangian function included into optimal cost functional. I want to know, if Lagrangian (in control terminology, NOT optimization), is convex in (x,u), Lipschitz, monotone-increasing or strictly positive (?). I want to know the assumptions only. Notice the attachment. My ultimate goal is to decipher, whether the cost function J(u), is a convex function of u, or not?