Functions integrable on a set and at a filter #
We define integrable_on f s μ := integrable f (μ.restrict s)
and prove theorems like
integrable_on_union : integrable_on f (s ∪ t) μ ↔ integrable_on f s μ ∧ integrable_on f t μ
.
Next we define a predicate integrable_at_filter (f : α → E) (l : filter α) (μ : measure α)
saying that f
is integrable at some set s ∈ l
and prove that a measurable function is integrable
at l
with respect to μ
provided that f
is bounded above at l ⊓ μ.ae
and μ
is finite
at l
.
A function f
is measurable at filter l
w.r.t. a measure μ
if it is ae-measurable
w.r.t. μ.restrict s
for some s ∈ l
.
Equations
- measurable_at_filter f l μ = ∃ (s : set α) (H : s ∈ l), ae_measurable f (measure_theory.measure.restrict μ s)
A function is integrable_on
a set s
if it is almost everywhere measurable on s
and if the
integral of its pointwise norm over s
is less than infinity.
Equations
We say that a function f
is integrable at filter l
if it is integrable on some
set s ∈ l
. Equivalently, it is eventually integrable on s
in l.lift' powerset
.
Equations
- measure_theory.integrable_at_filter f l μ = ∃ (s : set α) (H : s ∈ l), measure_theory.integrable_on f s μ
Alias of integrable_at_filter.inf_ae_iff
.
If μ
is a measure finite at filter l
and f
is a function such that its norm is bounded
above at l
, then f
is integrable at l
.
Alias of measure.finite_at_filter.integrable_at_filter_of_tendsto_ae
.
Alias of measure.finite_at_filter.integrable_at_filter_of_tendsto
.
If a function is integrable at 𝓝[s] x
for each point x
of a compact set s
, then it is
integrable on s
.
A function which is continuous on a set s
is almost everywhere measurable with respect to
μ.restrict s
.
A function f
continuous on a compact set s
is integrable on this set with respect to any
locally finite measure.
A continuous function f
is integrable on any compact set with respect to any locally finite
measure.
A continuous function with compact closure of the support is integrable on the whole space.