Lp space #
This file provides the space Lp E p μ
as the subtype of elements of α →ₘ[μ] E
(see MeasureTheory.AEEqFun
) such that eLpNorm f p μ
is finite.
For 1 ≤ p
, eLpNorm
defines a norm and Lp
is a complete metric space
(the latter is proved at Mathlib.MeasureTheory.Function.LpSpace.Complete
).
Main definitions #
Lp E p μ
: elements ofα →ₘ[μ] E
such thateLpNorm f p μ
is finite. Defined as anAddSubgroup
ofα →ₘ[μ] E
.
Lipschitz functions vanishing at zero act by composition on Lp
. We define this action, and prove
that it is continuous. In particular,
ContinuousLinearMap.compLp
defines the action onLp
of a continuous linear map.Lp.posPart
is the positive part of anLp
function.Lp.negPart
is the negative part of anLp
function.
Notations #
Implementation #
Since Lp
is defined as an AddSubgroup
, dot notation does not work. Use Lp.Measurable f
to
say that the coercion of f
to a genuine function is measurable, instead of the non-working
f.Measurable
.
To prove that two Lp
elements are equal, it suffices to show that their coercions to functions
coincide almost everywhere (this is registered as an ext
rule). This can often be done using
filter_upwards
. For instance, a proof from first principles that f + (g + h) = (f + g) + h
could read (in the Lp
namespace)
example (f g h : Lp E p μ) : (f + g) + h = f + (g + h) := by
ext1
filter_upwards [coeFn_add (f + g) h, coeFn_add f g, coeFn_add f (g + h), coeFn_add g h]
with _ ha1 ha2 ha3 ha4
simp only [ha1, ha2, ha3, ha4, add_assoc]
The lemma coeFn_add
states that the coercion of f + g
coincides almost everywhere with the sum
of the coercions of f
and g
. All such lemmas use coeFn
in their name, to distinguish the
function coercion from the coercion to almost everywhere defined functions.
Lp space #
The space of equivalence classes of measurable functions for which eLpNorm f p μ < ∞
.
Alias of MeasureTheory.MemLp.eLpNorm_mk_lt_top
.
Lp space
Equations
Instances For
α →₁[μ] E
is the type of L¹
or integrable functions from α
to E
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
α →₂[μ] E
is the type of L²
or square-integrable functions from α
to E
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
make an element of Lp from a function verifying MemLp
Equations
- MeasureTheory.MemLp.toLp f h_mem_ℒp = ⟨MeasureTheory.AEEqFun.mk f ⋯, ⋯⟩
Instances For
Equations
- MeasureTheory.Lp.instCoeFun = { coe := fun (f : ↥(MeasureTheory.Lp E p μ)) => ↑↑f }
Alias of MeasureTheory.Lp.mem_Lp_iff_memLp
.
Alias of MeasureTheory.Lp.memLp
.
Equations
- MeasureTheory.Lp.instNorm = { norm := fun (f : ↥(MeasureTheory.Lp E p μ)) => (MeasureTheory.eLpNorm (↑↑f) p μ).toReal }
Equations
- MeasureTheory.Lp.instNNNorm = { nnnorm := fun (f : ↥(MeasureTheory.Lp E p μ)) => ⟨‖f‖, ⋯⟩ }
Equations
- MeasureTheory.Lp.instDist = { dist := fun (f g : ↥(MeasureTheory.Lp E p μ)) => ‖f - g‖ }
Equations
- MeasureTheory.Lp.instEDist = { edist := fun (f g : ↥(MeasureTheory.Lp E p μ)) => MeasureTheory.eLpNorm (↑↑f - ↑↑g) p μ }
Alias of MeasureTheory.Lp.enorm_def
.
Alias of MeasureTheory.Lp.enorm_toLp
.
Equations
- One or more equations did not get rendered due to their size.
The 𝕜
-submodule of elements of α →ₘ[μ] E
whose Lp
norm is finite. This is Lp E p μ
,
with extra structure.
Equations
- MeasureTheory.Lp.LpSubmodule 𝕜 E p μ = { toAddSubmonoid := (MeasureTheory.Lp E p μ).toAddSubmonoid, smul_mem' := ⋯ }
Instances For
Equations
Equations
- MeasureTheory.Lp.instNormedSpace = { toModule := MeasureTheory.Lp.instModule, norm_smul_le := ⋯ }
Alias of MeasureTheory.MemLp.norm_rpow_div
.
Alias of MeasureTheory.memLp_norm_rpow_iff
.
Alias of MeasureTheory.MemLp.norm_rpow
.
Composition with a measure preserving function #
Composition of an L^p
function with a measure preserving function is an L^p
function.
Equations
- MeasureTheory.Lp.compMeasurePreserving f hf = { toFun := fun (g : ↥(MeasureTheory.Lp E p μb)) => ⟨(↑g).compMeasurePreserving f hf, ⋯⟩, map_zero' := ⋯, map_add' := ⋯ }
Instances For
MeasureTheory.Lp.compMeasurePreserving
as a linear map.
Equations
- MeasureTheory.Lp.compMeasurePreservingₗ 𝕜 f hf = { toFun := (↑(MeasureTheory.Lp.compMeasurePreserving f hf)).toFun, map_add' := ⋯, map_smul' := ⋯ }
Instances For
MeasureTheory.Lp.compMeasurePreserving
as a linear isometry.
Equations
- MeasureTheory.Lp.compMeasurePreservingₗᵢ 𝕜 f hf = { toLinearMap := MeasureTheory.Lp.compMeasurePreservingₗ 𝕜 f hf, norm_map' := ⋯ }
Instances For
Composition on L^p
#
We show that Lipschitz functions vanishing at zero act by composition on L^p
, and specialize
this to the composition with continuous linear maps, and to the definition of the positive
part of an L^p
function.
Alias of LipschitzWith.comp_memLp
.
When g
is a Lipschitz function sending 0
to 0
and f
is in Lp
, then g ∘ f
is well
defined as an element of Lp
.
Equations
- hg.compLp g0 f = ⟨MeasureTheory.AEEqFun.comp g ⋯ ↑f, ⋯⟩
Instances For
Composing f : Lp
with L : E →L[𝕜] F
.
Instances For
Alias of ContinuousLinearMap.comp_memLp
.
Alias of ContinuousLinearMap.comp_memLp'
.
Alias of MeasureTheory.MemLp.ofReal
.
Alias of MeasureTheory.memLp_re_im_iff
.
Composing f : Lp E p μ
with L : E →L[𝕜] F
, seen as a 𝕜
-linear map on Lp E p μ
.
Equations
- ContinuousLinearMap.compLpₗ p μ L = { toFun := fun (f : ↥(MeasureTheory.Lp E p μ)) => L.compLp f, map_add' := ⋯, map_smul' := ⋯ }
Instances For
Composing f : Lp E p μ
with L : E →L[𝕜] F
, seen as a continuous 𝕜
-linear map on
Lp E p μ
. See also the similar
LinearMap.compLeft
for functions,ContinuousLinearMap.compLeftContinuous
for continuous functions,ContinuousLinearMap.compLeftContinuousBounded
for bounded continuous functions,ContinuousLinearMap.compLeftContinuousCompact
for continuous functions on compact spaces.
Equations
- ContinuousLinearMap.compLpL p μ L = (ContinuousLinearMap.compLpₗ p μ L).mkContinuous ‖L‖ ⋯
Instances For
Alias of MeasureTheory.MemLp.pos_part
.
Alias of MeasureTheory.MemLp.neg_part
.
Positive part of a function in L^p
.
Equations
Instances For
Negative part of a function in L^p
.
Equations
Instances For
A version of Markov's inequality with elements of Lp.
A version of Markov's inequality with elements of Lp.
A version of Markov's inequality with elements of Lp.
A version of Markov's inequality with elements of Lp.
Alias of MeasureTheory.Lp.pow_mul_meas_ge_le_enorm
.
A version of Markov's inequality with elements of Lp.
Alias of MeasureTheory.Lp.mul_meas_ge_le_pow_enorm
.
A version of Markov's inequality with elements of Lp.
Alias of MeasureTheory.Lp.mul_meas_ge_le_pow_enorm'
.
A version of Markov's inequality with elements of Lp.
Alias of MeasureTheory.Lp.meas_ge_le_mul_pow_enorm
.
A version of Markov's inequality with elements of Lp.