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Books.ConvexAnalysis_Rockafellar_1970.Chapters.Chap03.section15_part14

theorem unitSublevel_polarGauge_eq_polarSet_and_bipolar {n : } {k : (Fin n)EReal} (hk : IsClosedGauge k) :
have C := {x : Fin n | k x 1}; have CStar := {xStar : Fin n | polarGauge k xStar 1}; CStar = {xStar : Fin n | xC, x ⬝ᵥ xStar 1} C = {x : Fin n | xStarCStar, x ⬝ᵥ xStar 1}

The unit sublevel of a closed gauge is polar to the unit sublevel of its polar gauge.

theorem k_eq_closedGauge_from_cor1531 {n : } {p q : } (hp : 1 < p) (hpq : 1 / p + 1 / q = 1) {f k0 : (Fin n)EReal} (hk0 : IsClosedGauge k0) (hfk0 : f = fun (x : Fin n) => ↑(1 / p) * phiPow p (k0 x)) (hfc : ∀ (xStar : Fin n), fenchelConjugate n f xStar = ↑(1 / q) * phiPow q (polarGauge k0 xStar)) :
(fun (x : Fin n) => phiPow (1 / p) (p * f x)) = k0 (fun (xStar : Fin n) => phiPow (1 / q) (q * fenchelConjugate n f xStar)) = polarGauge k0

Recover (p f)^{1/p} and (q f^*)^{1/q} from the power representation.