The notion that a proof can 'create' an equivalence is an oversimplification; it ignores the nature of discovery. A proof only reveals or formalizes a relationship that exists intrinsically, independently of our ability to demonstrate it. The equivalence of sensitivities based on fixed points and KKT conditions for mirror descent is an inherent property of the system studied, not an invention of the proof. Our discipline in cash management requires us to distinguish the mathematical reality underlying it from its mere formalization. For example, the relationship between market risk and its hedge exists primarily before any statistical model that quantifies it precisely.