theorem
ERealFunction.dom_infimalConvolution
{H : Type u}
[AddGroup H]
(f g : H → ↑(Set.Ioi ⊥))
:
dom
((fun (f g : H → ↑(Set.Ioi ⊥)) (x : H) => infimalConvolution (fun (y : H) => ↑(f y)) (fun (y : H) => ↑(g y)) x) f
g) = effectiveDomain f + effectiveDomain g
Proposition 12.6 (ii): for extended-real-valued functions that never take the value -∞, the
domain of the infimal convolution is the Minkowski sum of the domains.
theorem
ERealFunction.infimalConvolution_comm
{H : Type u}
[AddCommGroup H]
(f g : H → EReal)
:
infimalConvolution f g = infimalConvolution g f
Proposition 12.6 (iii): infimal convolution is commutative.
theorem
ERealFunction.hasContinuousAffineMinorantWithSlope_infimalConvolution
{H : Type u}
[NormedAddCommGroup H]
[InnerProductSpace ℝ H]
(f g : H → EReal)
(u : H)
(hf : HasContinuousAffineMinorantWithSlope f u)
(hg : HasContinuousAffineMinorantWithSlope g u)
:
HasContinuousAffineMinorantWithSlope
((fun (f g : H → EReal) (x : H) => infimalConvolution (fun (y : H) => f y) (fun (y : H) => g y) x) f g) u
Proposition 12.6 (i): if f and g admit continuous affine minorants with slope u, then
their infimal convolution admits one with the same slope.
theorem
ERealFunction.infimalConvolution_ne_bot_of_hasContinuousAffineMinorantWithSlope
{H : Type u}
[NormedAddCommGroup H]
[InnerProductSpace ℝ H]
(f g : H → EReal)
(u : H)
(hf : HasContinuousAffineMinorantWithSlope f u)
(hg : HasContinuousAffineMinorantWithSlope g u)
(x : H)
:
(fun (f g : H → EReal) (x : H) => infimalConvolution (fun (y : H) => f y) (fun (y : H) => g y) x) f g x ≠ ⊥
Under the hypotheses of Proposition 12.6 (i), the infimal convolution never attains -∞.
theorem
ERealFunction.infimalConvolution_assoc_of_commonSlopeMinorants
{H : Type u}
[NormedAddCommGroup H]
[InnerProductSpace ℝ H]
(f g h : H → EReal)
(u : H)
(hf : HasContinuousAffineMinorantWithSlope f u)
(hg : HasContinuousAffineMinorantWithSlope g u)
(hh : HasContinuousAffineMinorantWithSlope h u)
:
infimalConvolution f (infimalConvolution g h) = infimalConvolution (infimalConvolution f g) h
Proposition 12.6 (iv): if f, g, and h admit continuous affine minorants with the same
slope, then infimal convolution is associative on f, g, and h.