Compatibility of algebraic operations with metric space structures

In this file we define mixin typeclasses LipschitzMul, LipschitzAdd, BoundedSMul expressing compatibility of multiplication, addition and scalar-multiplication operations with an underlying metric space structure. The intended use case is to abstract certain properties shared by normed groups and by R≥0.

Implementation notes

We deduce a ContinuousMul instance from LipschitzMul, etc. In principle there should be an intermediate typeclass for uniform spaces, but the algebraic hierarchy there (see UniformGroup) is structured differently.

class LipschitzAdd (β : Type u_2) [PseudoMetricSpace β] [AddMonoid β] : Prop

Class LipschitzAdd M says that the addition (+) : X × X → X is Lipschitz jointly in the two arguments.

• lipschitz_add : ∃ (C : NNReal), LipschitzWith C fun (p : β × β) => p.1 + p.2

theorem LipschitzAdd.lipschitz_add {β : Type u_2} [PseudoMetricSpace β] [AddMonoid β] [self : LipschitzAdd β] : ∃ (C : NNReal), LipschitzWith C fun (p : β × β) => p.1 + p.2

class LipschitzMul (β : Type u_2) [PseudoMetricSpace β] [Monoid β] : Prop

Class LipschitzMul M says that the multiplication (*) : X × X → X is Lipschitz jointly in the two arguments.

• lipschitz_mul : ∃ (C : NNReal), LipschitzWith C fun (p : β × β) => p.1 * p.2

theorem LipschitzMul.lipschitz_mul {β : Type u_2} [PseudoMetricSpace β] [Monoid β] [self : LipschitzMul β] : ∃ (C : NNReal), LipschitzWith C fun (p : β × β) => p.1 * p.2

def LipschitzAdd.C (β : Type u_2) [PseudoMetricSpace β] [AddMonoid β] [_i : LipschitzAdd β] : NNReal

The Lipschitz constant of an AddMonoid β satisfying LipschitzAdd

Equations

• LipschitzAdd.C β = Classical.choose ⋯

def LipschitzMul.C (β : Type u_2) [PseudoMetricSpace β] [Monoid β] [_i : LipschitzMul β] : NNReal

The Lipschitz constant of a monoid β satisfying LipschitzMul

Equations

• LipschitzMul.C β = Classical.choose ⋯

theorem lipschitzWith_lipschitz_const_add_edist {β : Type u_2} [PseudoMetricSpace β] [AddMonoid β] [_i : LipschitzAdd β] : LipschitzWith (LipschitzAdd.C β) fun (p : β × β) => p.1 + p.2

theorem lipschitzWith_lipschitz_const_mul_edist {β : Type u_2} [PseudoMetricSpace β] [Monoid β] [_i : LipschitzMul β] : LipschitzWith (LipschitzMul.C β) fun (p : β × β) => p.1 * p.2

theorem lipschitz_with_lipschitz_const_add {β : Type u_2} [PseudoMetricSpace β] [AddMonoid β] [LipschitzAdd β] (p : β × β) (q : β × β) : dist (p.1 + p.2) (q.1 + q.2) ≤ ↑(LipschitzAdd.C β) * dist p q

theorem lipschitz_with_lipschitz_const_mul {β : Type u_2} [PseudoMetricSpace β] [Monoid β] [LipschitzMul β] (p : β × β) (q : β × β) : dist (p.1 * p.2) (q.1 * q.2) ≤ ↑(LipschitzMul.C β) * dist p q

@[instance 100]

instance LipschitzAdd.continuousAdd {β : Type u_2} [PseudoMetricSpace β] [AddMonoid β] [LipschitzAdd β] : ContinuousAdd β

Equations

• ⋯ = ⋯

@[instance 100]

instance LipschitzMul.continuousMul {β : Type u_2} [PseudoMetricSpace β] [Monoid β] [LipschitzMul β] : ContinuousMul β

Equations

• ⋯ = ⋯

instance AddSubmonoid.lipschitzAdd {β : Type u_2} [PseudoMetricSpace β] [AddMonoid β] [LipschitzAdd β] (s : AddSubmonoid β) : LipschitzAdd { x : β // x ∈ s }

Equations

• ⋯ = ⋯

instance Submonoid.lipschitzMul {β : Type u_2} [PseudoMetricSpace β] [Monoid β] [LipschitzMul β] (s : Submonoid β) : LipschitzMul { x : β // x ∈ s }

Equations

• ⋯ = ⋯

instance AddOpposite.lipschitzAdd {β : Type u_2} [PseudoMetricSpace β] [AddMonoid β] [LipschitzAdd β] : LipschitzAdd βᵃᵒᵖ

Equations

• ⋯ = ⋯

instance MulOpposite.lipschitzMul {β : Type u_2} [PseudoMetricSpace β] [Monoid β] [LipschitzMul β] : LipschitzMul βᵐᵒᵖ

Equations

• ⋯ = ⋯

instance Real.hasLipschitzAdd : LipschitzAdd ℝ

Equations

• Real.hasLipschitzAdd = ⋯

instance NNReal.hasLipschitzAdd : LipschitzAdd NNReal

Equations

• NNReal.hasLipschitzAdd = ⋯

class BoundedSMul (α : Type u_1) (β : Type u_2) [PseudoMetricSpace α] [PseudoMetricSpace β] [Zero α] [Zero β] [SMul α β] : Prop

Mixin typeclass on a scalar action of a metric space α on a metric space β both with distinguished points 0, requiring compatibility of the action in the sense that dist (x • y₁) (x • y₂) ≤ dist x 0 * dist y₁ y₂ and dist (x₁ • y) (x₂ • y) ≤ dist x₁ x₂ * dist y 0.

• dist_smul_pair' : ∀ (x : α) (y₁ y₂ : β), dist (x • y₁) (x • y₂) ≤ dist x 0 * dist y₁ y₂
• dist_pair_smul' : ∀ (x₁ x₂ : α) (y : β), dist (x₁ • y) (x₂ • y) ≤ dist x₁ x₂ * dist y 0

theorem BoundedSMul.dist_smul_pair' {α : Type u_1} {β : Type u_2} [PseudoMetricSpace α] [PseudoMetricSpace β] [Zero α] [Zero β] [SMul α β] [self : BoundedSMul α β] (x : α) (y₁ : β) (y₂ : β) : dist (x • y₁) (x • y₂) ≤ dist x 0 * dist y₁ y₂

theorem BoundedSMul.dist_pair_smul' {α : Type u_1} {β : Type u_2} [PseudoMetricSpace α] [PseudoMetricSpace β] [Zero α] [Zero β] [SMul α β] [self : BoundedSMul α β] (x₁ : α) (x₂ : α) (y : β) : dist (x₁ • y) (x₂ • y) ≤ dist x₁ x₂ * dist y 0

theorem dist_smul_pair {α : Type u_1} {β : Type u_2} [PseudoMetricSpace α] [PseudoMetricSpace β] [Zero α] [Zero β] [SMul α β] [BoundedSMul α β] (x : α) (y₁ : β) (y₂ : β) : dist (x • y₁) (x • y₂) ≤ dist x 0 * dist y₁ y₂

theorem dist_pair_smul {α : Type u_1} {β : Type u_2} [PseudoMetricSpace α] [PseudoMetricSpace β] [Zero α] [Zero β] [SMul α β] [BoundedSMul α β] (x₁ : α) (x₂ : α) (y : β) : dist (x₁ • y) (x₂ • y) ≤ dist x₁ x₂ * dist y 0

@[instance 100]

instance BoundedSMul.continuousSMul {α : Type u_1} {β : Type u_2} [PseudoMetricSpace α] [PseudoMetricSpace β] [Zero α] [Zero β] [SMul α β] [BoundedSMul α β] : ContinuousSMul α β

The typeclass BoundedSMul on a metric-space scalar action implies continuity of the action.

Equations

• ⋯ = ⋯

instance Real.boundedSMul : BoundedSMul ℝ ℝ

Equations

• Real.boundedSMul = ⋯

instance NNReal.boundedSMul : BoundedSMul NNReal NNReal

Equations

• NNReal.boundedSMul = ⋯

instance BoundedSMul.op {α : Type u_1} {β : Type u_2} [PseudoMetricSpace α] [PseudoMetricSpace β] [Zero α] [Zero β] [SMul α β] [BoundedSMul α β] [SMul αᵐᵒᵖ β] [IsCentralScalar α β] : BoundedSMul αᵐᵒᵖ β

If a scalar is central, then its right action is bounded when its left action is.

Equations

• ⋯ = ⋯

instance instLipschitzAddAdditiveOfLipschitzMul (α : Type u_1) [PseudoMetricSpace α] [Monoid α] [LipschitzMul α] : LipschitzAdd (Additive α)

Equations

• ⋯ = ⋯

instance instLipschitzMulMultiplicativeOfLipschitzAdd (α : Type u_1) [PseudoMetricSpace α] [AddMonoid α] [LipschitzAdd α] : LipschitzMul (Multiplicative α)

Equations

• ⋯ = ⋯

instance instLipschitzAddOrderDual (α : Type u_1) [PseudoMetricSpace α] [AddMonoid α] [LipschitzAdd α] : LipschitzAdd αᵒᵈ

Equations

• ⋯ = inst

instance instLipschitzMulOrderDual (α : Type u_1) [PseudoMetricSpace α] [Monoid α] [LipschitzMul α] : LipschitzMul αᵒᵈ

Equations

• ⋯ = inst

instance Pi.instBoundedSMul {ι : Type u_3} [Fintype ι] {α : Type u_4} {β : ι → Type u_5} [PseudoMetricSpace α] [(i : ι) → PseudoMetricSpace (β i)] [Zero α] [(i : ι) → Zero (β i)] [(i : ι) → SMul α (β i)] [∀ (i : ι), BoundedSMul α (β i)] : BoundedSMul α ((i : ι) → β i)

Equations

• ⋯ = ⋯

instance Pi.instBoundedSMul' {ι : Type u_3} [Fintype ι] {α : ι → Type u_4} {β : ι → Type u_5} [(i : ι) → PseudoMetricSpace (α i)] [(i : ι) → PseudoMetricSpace (β i)] [(i : ι) → Zero (α i)] [(i : ι) → Zero (β i)] [(i : ι) → SMul (α i) (β i)] [∀ (i : ι), BoundedSMul (α i) (β i)] : BoundedSMul ((i : ι) → α i) ((i : ι) → β i)

Equations

• ⋯ = ⋯

instance Prod.instBoundedSMul {α : Type u_4} {β : Type u_5} {γ : Type u_6} [PseudoMetricSpace α] [PseudoMetricSpace β] [PseudoMetricSpace γ] [Zero α] [Zero β] [Zero γ] [SMul α β] [SMul α γ] [BoundedSMul α β] [BoundedSMul α γ] : BoundedSMul α (β × γ)

Equations

• ⋯ = ⋯