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ConvexAnalysisMonotoneOperators_BauschkeCombettes_2017.Chap12.Proposition_12_15

theorem ERealFunction.convexOn_univ_toReal_normPowerEnvelope_of_mem_gammaZero {H : Type u} [NormedAddCommGroup H] [InnerProductSpace H] [CompleteSpace H] (f : H(Set.Ioi )) (γ : PosReal) (p : (Set.Ici 1)) (hf : f Γ₀(H)) (hp : 1 < p) :
_root_.ConvexOn Set.univ fun (x : H) => (normPowerEnvelope f p γ x).toReal

Proposition 12.15 (1): if f ∈ Γ₀(H), γ ∈ ℝ_{++}, and p > 1, then the real-valued representative of the p-power envelope is convex on H.

theorem ERealFunction.normPowerEnvelope_mem_Ioo_of_mem_gammaZero {H : Type u} [NormedAddCommGroup H] [InnerProductSpace H] [CompleteSpace H] (f : H(Set.Ioi )) (γ : PosReal) (p : (Set.Ici 1)) (hf : f Γ₀(H)) (hp : 1 < p) (x : H) :
normPowerEnvelope f p γ x Set.Ioo

Proposition 12.15 (2): if f ∈ Γ₀(H), γ ∈ ℝ_{++}, and p > 1, then the p-power envelope is real-valued at every point of H.

theorem ERealFunction.continuous_toReal_normPowerEnvelope_of_mem_gammaZero {H : Type u} [NormedAddCommGroup H] [InnerProductSpace H] [CompleteSpace H] (f : H(Set.Ioi )) (γ : PosReal) (p : (Set.Ici 1)) (hf : f Γ₀(H)) (hp : 1 < p) :
Continuous fun (x : H) => (normPowerEnvelope f p γ x).toReal

Proposition 12.15 (3): if f ∈ Γ₀(H), γ ∈ ℝ_{++}, and p > 1, then the real-valued representative of the p-power envelope is continuous on H.

theorem ERealFunction.exactAt_and_existsUnique_mem_argmin_normPowerEnvelope_of_mem_gammaZero {H : Type u} [NormedAddCommGroup H] [InnerProductSpace H] [CompleteSpace H] (f : H(Set.Ioi )) (γ : PosReal) (p : (Set.Ici 1)) (hf : f Γ₀(H)) (hp : 1 < p) (x : H) :
infimalConvolution.ExactAt f (normPowerKernel p γ) x ∃! y : H, y Argmin fun (z : H) => (f z) + (normPowerKernel p γ (x - z))

Proposition 12.15 (4): for f ∈ Γ₀(H), γ ∈ ℝ_{++}, p > 1, and every x ∈ H, the infimal convolution defining the p-power regularization is exact at x, and the translated objective y ↦ f y + ‖x - y‖^p / (γ p) has a unique global minimizer.