ℒp space #
This file describes properties of almost everywhere strongly measurable functions with finite
p
-seminorm, denoted by eLpNorm f p μ
and defined for p:ℝ≥0∞
as 0
if p=0
,
(∫ ‖f a‖^p ∂μ) ^ (1/p)
for 0 < p < ∞
and essSup ‖f‖ μ
for p=∞
.
The Prop-valued Memℒp f p μ
states that a function f : α → E
has finite p
-seminorm
and is almost everywhere strongly measurable.
Main definitions #
eLpNorm' f p μ
:(∫ ‖f a‖^p ∂μ) ^ (1/p)
forf : α → F
andp : ℝ
, whereα
is a measurable space andF
is a normed group.eLpNormEssSup f μ
: seminorm inℒ∞
, equal to the essential supremumessSup ‖f‖ μ
.eLpNorm f p μ
: forp : ℝ≥0∞
, seminorm inℒp
, equal to0
forp=0
, toeLpNorm' f p μ
for0 < p < ∞
and toeLpNormEssSup f μ
forp = ∞
.Memℒp f p μ
: property that the functionf
is almost everywhere strongly measurable and has finitep
-seminorm for the measureμ
(eLpNorm f p μ < ∞
)
ℒp seminorm #
We define the ℒp seminorm, denoted by eLpNorm f p μ
. For real p
, it is given by an integral
formula (for which we use the notation eLpNorm' f p μ
), and for p = ∞
it is the essential
supremum (for which we use the notation eLpNormEssSup f μ
).
We also define a predicate Memℒp f p μ
, requesting that a function is almost everywhere
measurable and has finite eLpNorm f p μ
.
This paragraph is devoted to the basic properties of these definitions. It is constructed as
follows: for a given property, we prove it for eLpNorm'
and eLpNormEssSup
when it makes sense,
deduce it for eLpNorm
, and translate it in terms of Memℒp
.
(∫ ‖f a‖^q ∂μ) ^ (1/q)
, which is a seminorm on the space of measurable functions for which
this quantity is finite
seminorm for ℒ∞
, equal to the essential supremum of ‖f‖
.
Equations
- MeasureTheory.eLpNormEssSup f μ = essSup (fun (x : α) => ‖f x‖ₑ) μ
ℒp
seminorm, equal to 0
for p=0
, to (∫ ‖f a‖^p ∂μ) ^ (1/p)
for 0 < p < ∞
and to
essSup ‖f‖ μ
for p = ∞
.
The property that f:α→E
is ae strongly measurable and (∫ ‖f a‖^p ∂μ)^(1/p)
is finite
if p < ∞
, or essSup f < ∞
if p = ∞
.
Equations
- MeasureTheory.Memℒp f p μ = (MeasureTheory.AEStronglyMeasurable f μ ∧ MeasureTheory.eLpNorm f p μ < ⊤)
Alias of MeasureTheory.lintegral_rpow_enorm_eq_rpow_eLpNorm'
.
Alias of MeasureTheory.lintegral_rpow_enorm_lt_top_of_eLpNorm'_lt_top
.
Alias of MeasureTheory.lintegral_rpow_enorm_lt_top_of_eLpNorm_lt_top
.
Alias of MeasureTheory.Memℒp.zero
.
Alias of MeasureTheory.Memℒp.zero'
.
Alias of MeasureTheory.Memℒp.of_le
.
Alias of MeasureTheory.eLpNorm_indicator_eq_eLpNorm_restrict
.
For a function f
with support in s
, the Lᵖ norms of f
with respect to μ
and
μ.restrict s
are the same.
See eLpNorm_smul_measure_of_ne_zero'
for a version with scalar multiplication by ℝ≥0
.
See eLpNorm_smul_measure_of_ne_zero
for a version with scalar multiplication by ℝ≥0∞
.
See eLpNorm_smul_measure_of_ne_top'
for a version with scalar multiplication by ℝ≥0
.
See eLpNorm_smul_measure_of_ne_top'
for a version with scalar multiplication by ℝ≥0∞
.
When c
is negative, ‖f x‖ ≤ c * ‖g x‖
is nonsense and forces both f
and g
to have an
eLpNorm
of 0
.
Bounded actions by normed rings #
In this section we show inequalities on the norm.
Bounded actions by normed division rings #
The inequalities in the previous section are now tight.
A continuous function with compact support belongs to L^∞
.
See Continuous.memℒp_of_hasCompactSupport
for a version for L^p
.
A single function that is Memℒp f p μ
is tight with respect to μ
.