Operator norm: bilinear maps #
This file contains lemmas concerning operator norm as applied to bilinear maps E × F → G,
interpreted as linear maps E → F → G as usual (and similarly for semilinear variants).
Create a bilinear map (represented as a map E →L[𝕜] F →L[𝕜] G) from the corresponding linear
map and existence of a bound on the norm of the image. The linear map can be constructed using
LinearMap.mk₂.
If you have an explicit bound, use LinearMap.mkContinuous₂ instead, as a norm estimate will
follow automatically in LinearMap.mkContinuous₂_norm_le.
Equations
- f.mkContinuousOfExistsBound₂ h = { toFun := fun (x : E) => (f x).mkContinuousOfExistsBound ⋯, map_add' := ⋯, map_smul' := ⋯ }.mkContinuousOfExistsBound ⋯
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Create a bilinear map (represented as a map E →L[𝕜] F →L[𝕜] G) from the corresponding linear
map and a bound on the norm of the image. The linear map can be constructed using
LinearMap.mk₂. Lemmas LinearMap.mkContinuous₂_norm_le' and LinearMap.mkContinuous₂_norm_le
provide estimates on the norm of an operator constructed using this function.
Equations
- f.mkContinuous₂ C hC = f.mkContinuousOfExistsBound₂ ⋯
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Given a bilinear map, convert it to a continuous bilinear map if there exists a continuous bilinear map which coincides with it. This may seem silly: why not use the witness directly? The reason to use this is good definitional behavior: in use cases for normable spaces, the witness is constructed by putting a norm on the space, so it has a complicated definition which the kernel struggles with, while the output of the current definition is definitionally much nicer.
Equations
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Flip the order of arguments of a continuous bilinear map.
For a version bundled as LinearIsometryEquiv, see ContinuousLinearMap.flipL.
Equations
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Flip the order of arguments of a continuous bilinear map.
This is a version bundled as a LinearIsometryEquiv.
For an unbundled version see ContinuousLinearMap.flip.
Equations
- One or more equations did not get rendered due to their size.
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Flip the order of arguments of a continuous bilinear map.
This is a version bundled as a LinearIsometryEquiv.
For an unbundled version see ContinuousLinearMap.flip.
Equations
- ContinuousLinearMap.flipₗᵢ 𝕜 E Fₗ Gₗ = { toFun := ContinuousLinearMap.flip, map_add' := ⋯, map_smul' := ⋯, invFun := ContinuousLinearMap.flip, left_inv := ⋯, right_inv := ⋯, norm_map' := ⋯ }
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The continuous semilinear map obtained by applying a continuous semilinear map at a given vector.
This is the continuous version of LinearMap.applyₗ.
Equations
- ContinuousLinearMap.apply' F' σ₁₂ = (ContinuousLinearMap.id 𝕜₂ (E' →SL[σ₁₂] F')).flip
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The continuous semilinear map obtained by applying a continuous semilinear map at a given vector.
This is the continuous version of LinearMap.applyₗ.
Equations
- ContinuousLinearMap.apply 𝕜 Fₗ' = (ContinuousLinearMap.id 𝕜 (E' →L[𝕜] Fₗ')).flip
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Composition of continuous semilinear maps as a semibilinear map.
Do not use: use instead the version compSL which outputs a continuous semibilinear map.
Equations
- ContinuousLinearMap.compSLₗ E' F' G' σ₁₂ σ₂₃ = LinearMap.mk₂'ₛₗ (RingHom.id 𝕜₃) σ₂₃ ContinuousLinearMap.comp ⋯ ⋯ ⋯ ⋯
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Composition of continuous semilinear maps as a continuous semibilinear map.
Equations
- ContinuousLinearMap.compSL E' F' G' σ₁₂ σ₂₃ = (ContinuousLinearMap.compSLₗ E' F' G' σ₁₂ σ₂₃).mkContinuous₂OfExists ⋯
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Composition of continuous linear maps as a continuous bilinear map.
Equations
- ContinuousLinearMap.compL 𝕜 E' Fₗ' Gₗ' = ContinuousLinearMap.compSL E' Fₗ' Gₗ' (RingHom.id 𝕜) (RingHom.id 𝕜)
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Apply L(x,-) pointwise to bilinear maps, as a continuous bilinear map
Equations
- ContinuousLinearMap.precompR Eₗ' L = ContinuousLinearMap.compL 𝕜 Eₗ' Fₗ' Gₗ' ∘SL L
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Apply L(-,y) pointwise to bilinear maps, as a continuous bilinear map
Equations
- ContinuousLinearMap.precompL Eₗ' L = (ContinuousLinearMap.precompR Eₗ' L.flip).flip
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Compose a bilinear map E' →SL[σ₁₃] F' →SL[σ₂₃] G' with two linear maps
E'' →SL[σ₁'] E' and F'' →SL[σ₂'] F'.
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Derivative of a continuous bilinear map f : E →L[𝕜] F →L[𝕜] G interpreted as a map E × F → G
at point p : E × F evaluated at q : E × F, as a continuous bilinear map.
Equations
- f.deriv₂ = f.bilinearComp (ContinuousLinearMap.fst 𝕜 E' Fₗ') (ContinuousLinearMap.snd 𝕜 E' Fₗ') + f.flip.bilinearComp (ContinuousLinearMap.snd 𝕜 E' Fₗ') (ContinuousLinearMap.fst 𝕜 E' Fₗ')
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The norm of the tensor product of a scalar linear map and of an element of a normed space is the product of the norms.
The non-negative norm of the tensor product of a scalar linear map and of an element of a normed space is the product of the non-negative norms.
ContinuousLinearMap.smulRight as a trilinear map:
smulRightLₗ (c : StrongDual 𝕜 E) (f : F) (x : E) = c x • f.
Do not use: use instead smulRightL which outputs a continuous trilinear map.
Equations
- ContinuousLinearMap.smulRightLₗ 𝕜 E' Fₗ' = { toFun := ContinuousLinearMap.smulRightₗ, map_add' := ⋯, map_smul' := ⋯ }
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ContinuousLinearMap.smulRight as a continuous trilinear map:
smulRightL (c : StrongDual 𝕜 E) (f : F) (x : E) = c x • f.
This is also known as a rank-one operator.
See also InnerProductSpace.rankOne for the rank-one operator on Hilbert spaces.
Equations
- ContinuousLinearMap.smulRightL 𝕜 E' Fₗ' = (ContinuousLinearMap.smulRightLₗ 𝕜 E' Fₗ').mkContinuous₂OfExists ⋯
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Convenience function for restricting the linearity of a bilinear map.