Typeclasses for measurability of operations #
In this file we define classes MeasurableMul etc. and prove dot-style lemmas
(Measurable.mul, AEMeasurable.mul etc). For binary operations we define two typeclasses:
MeasurableMulsays that both left and right multiplication are measurable;MeasurableMul₂says thatfun p : α × α => p.1 * p.2is measurable,
and similarly for other binary operations. The reason for introducing these classes is that in case
of topological space α equipped with the Borel σ-algebra, instances for MeasurableMul₂
etc. require α to have a second countable topology.
We define separate classes for MeasurableDiv/MeasurableSub
because on some types (e.g., ℕ, ℝ≥0∞) division and/or subtraction are not defined as a * b⁻¹ /
a + (-b).
For instances relating, e.g., ContinuousMul to MeasurableMul see file
MeasureTheory.BorelSpace.
Implementation notes #
For the heuristics of @[to_additive] it is important that the type with a multiplication
(or another multiplicative operations) is the first (implicit) argument of all declarations.
Tags #
measurable function, arithmetic operator
TODO #
- Uniformize the treatment of
powandsmul. - Use
@[to_additive]to sendMeasurablePowtoMeasurableSMul₂. - This might require changing the definition (swapping the arguments in the function that is
in the conclusion of
MeasurableSMul.)
Binary operations: (· + ·), (· * ·), (· - ·), (· / ·) #
We say that a type has MeasurableAdd if (· + c) and (· + c) are measurable functions.
For a typeclass assuming measurability of uncurry (· + ·) see MeasurableAdd₂.
- measurable_const_add (c : M) : Measurable fun (x : M) => c + x
- measurable_add_const (c : M) : Measurable fun (x : M) => x + c
Instances
We say that a type has MeasurableAdd₂ if uncurry (· + ·) is a measurable functions.
For a typeclass assuming measurability of (c + ·) and (· + c) see MeasurableAdd.
- measurable_add : Measurable fun (p : M × M) => p.1 + p.2
Instances
We say that a type has MeasurableMul if (c * ·) and (· * c) are measurable functions.
For a typeclass assuming measurability of uncurry (*) see MeasurableMul₂.
- measurable_const_mul (c : M) : Measurable fun (x : M) => c * x
- measurable_mul_const (c : M) : Measurable fun (x : M) => x * c
Instances
We say that a type has MeasurableMul₂ if uncurry (· * ·) is a measurable functions.
For a typeclass assuming measurability of (c * ·) and (· * c) see MeasurableMul.
- measurable_mul : Measurable fun (p : M × M) => p.1 * p.2
Instances
Compositional version of Measurable.mul for use by fun_prop.
Compositional version of Measurable.add for use by fun_prop.
A version of measurable_div_const that assumes MeasurableMul instead of
MeasurableDiv. This can be nice to avoid unnecessary type-class assumptions.
A version of measurable_sub_const that assumes MeasurableAdd instead of
MeasurableSub. This can be nice to avoid unnecessary type-class assumptions.
This class assumes that the map β × γ → β given by (x, y) ↦ x ^ y is measurable.
- measurable_pow : Measurable fun (p : β × γ) => p.1 ^ p.2
Instances
Monoid.Pow is measurable.
We say that a type has MeasurableSub if (c - ·) and (· - c) are measurable
functions. For a typeclass assuming measurability of uncurry (-) see MeasurableSub₂.
- measurable_const_sub (c : G) : Measurable fun (x : G) => c - x
- measurable_sub_const (c : G) : Measurable fun (x : G) => x - c
Instances
We say that a type has MeasurableSub₂ if uncurry (· - ·) is a measurable functions.
For a typeclass assuming measurability of (c - ·) and (· - c) see MeasurableSub.
- measurable_sub : Measurable fun (p : G × G) => p.1 - p.2
Instances
We say that a type has MeasurableDiv if (c / ·) and (· / c) are measurable functions.
For a typeclass assuming measurability of uncurry (· / ·) see MeasurableDiv₂.
- measurable_const_div (c : G₀) : Measurable fun (x : G₀) => c / x
- measurable_div_const (c : G₀) : Measurable fun (x : G₀) => x / c
Instances
We say that a type has MeasurableDiv₂ if uncurry (· / ·) is a measurable functions.
For a typeclass assuming measurability of (c / ·) and (· / c) see MeasurableDiv.
- measurable_div : Measurable fun (p : G₀ × G₀) => p.1 / p.2
Instances
We say that a type has MeasurableNeg if x ↦ -x is a measurable function.
- measurable_neg : Measurable Neg.neg
Instances
We say that a type has MeasurableInv if x ↦ x⁻¹ is a measurable function.
- measurable_inv : Measurable Inv.inv
Instances
Alias of measurable_inv_iff.
Alias of aemeasurable_inv_iff.
DivInvMonoid.Pow is measurable.
We say that the action of M on α has MeasurableConstVAdd if for each c the map
x ↦ c +ᵥ x is a measurable function.
- measurable_const_vadd (c : M) : Measurable fun (x : α) => c +ᵥ x
Instances
We say that the action of M on α has MeasurableConstSMul if for each c the map
x ↦ c • x is a measurable function.
- measurable_const_smul (c : M) : Measurable fun (x : α) => c • x
Instances
We say that the action of M on α has MeasurableVAdd if for each c the map x ↦ c +ᵥ x
is a measurable function and for each x the map c ↦ c +ᵥ x is a measurable function.
- measurable_vadd_const (x : α) : Measurable fun (x_1 : M) => x_1 +ᵥ x
Instances
We say that the action of M on α has MeasurableSMul if for each c the map x ↦ c • x
is a measurable function and for each x the map c ↦ c • x is a measurable function.
- measurable_smul_const (x : α) : Measurable fun (x_1 : M) => x_1 • x
Instances
We say that the action of M on α has MeasurableVAdd₂ if the map
(c, x) ↦ c +ᵥ x is a measurable function.
- measurable_vadd : Measurable (Function.uncurry fun (x1 : M) (x2 : α) => x1 +ᵥ x2)
Instances
We say that the action of M on α has Measurable_SMul₂ if the map
(c, x) ↦ c • x is a measurable function.
- measurable_smul : Measurable (Function.uncurry fun (x1 : M) (x2 : α) => x1 • x2)
Instances
Compositional version of Measurable.const_smul for use by fun_prop.
Compositional version of Measurable.const_vadd for use by fun_prop.
Alias of Measurable.fun_const_smul.
Compositional version of Measurable.const_smul for use by fun_prop.
Alias of AEMeasurable.fun_const_smul.
If a scalar is central, then its right action is measurable when its left action is.
Compositional version of Measurable.smul for use by fun_prop.
Compositional version of Measurable.vadd for use by fun_prop.
AddMonoid.SMul is measurable.
SubNegMonoid.SMulInt is measurable.
Equations
Equations
Opposite monoid #
If a scalar is central, then its right action is measurable when its left action is.
If a scalar is central, then its right action is measurable when its left action is.
Big operators: ∏ and ∑ #
Alias of List.measurable_sum.
Alias of List.measurable_prod.
Alias of List.aemeasurable_sum.
Alias of List.aemeasurable_prod.
Alias of Multiset.measurable_sum.
Alias of Multiset.measurable_prod.
Alias of Multiset.aemeasurable_sum.
Alias of Multiset.aemeasurable_prod.
Compositional version of Finset.measurable_prod for use by fun_prop.
Compositional version of Finset.measurable_sum for use by fun_prop.
Alias of Finset.measurable_sum_apply.
Compositional version of Finset.measurable_sum for use by fun_prop.
Alias of Finset.measurable_prod_apply.
Compositional version of Finset.measurable_prod for use by fun_prop.
Alias of Finset.aemeasurable_sum.
Alias of Finset.aemeasurable_prod.