[graycat]

> I think it is more productive to ask yourself what questions you want to answer

I second that. An old remark is, "We often find that a good question is more important than a good answer.", as I recall, due to Richard Bellman, say, the leading proponent of dynamic programming, i.e., usually a case of optimal control, either for the deterministic or stochastic (the system gets random exogenous inputs while we are trying to control it). Bellman was into a lot in pure and applied mathematics, engineering, medicine, etc. Bright guy. As I recall, his Ph.D. was in stability of solutions of initial value problems for ordinary differential equations, from Princeton.