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Ici_sup_hom : sup_hom α (upper_set α)
⟨Ici, Ici_sup⟩
def
upper_set.Ici_sup_hom
order.upper_lower
src/order/upper_lower/hom.lean
[ "order.upper_lower.basic", "order.hom.complete_lattice" ]
[ "sup_hom", "upper_set" ]
`upper_set.Ici` as a `sup_hom`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_Ici_sup_hom : (Ici_sup_hom : α → upper_set α) = Ici
rfl
lemma
upper_set.coe_Ici_sup_hom
order.upper_lower
src/order/upper_lower/hom.lean
[ "order.upper_lower.basic", "order.hom.complete_lattice" ]
[ "upper_set" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Ici_sup_hom_apply (a : α) : Ici_sup_hom a = (Ici a)
rfl
lemma
upper_set.Ici_sup_hom_apply
order.upper_lower
src/order/upper_lower/hom.lean
[ "order.upper_lower.basic", "order.hom.complete_lattice" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Ici_Sup_hom : Sup_hom α (upper_set α)
⟨Ici, λ s, (Ici_Sup s).trans Sup_image.symm⟩
def
upper_set.Ici_Sup_hom
order.upper_lower
src/order/upper_lower/hom.lean
[ "order.upper_lower.basic", "order.hom.complete_lattice" ]
[ "Sup_hom", "upper_set" ]
`upper_set.Ici` as a `Sup_hom`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_Ici_Sup_hom : (Ici_Sup_hom : α → upper_set α) = Ici
rfl
lemma
upper_set.coe_Ici_Sup_hom
order.upper_lower
src/order/upper_lower/hom.lean
[ "order.upper_lower.basic", "order.hom.complete_lattice" ]
[ "upper_set" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Ici_Sup_hom_apply (a : α) : Ici_Sup_hom a = Ici a
rfl
lemma
upper_set.Ici_Sup_hom_apply
order.upper_lower
src/order/upper_lower/hom.lean
[ "order.upper_lower.basic", "order.hom.complete_lattice" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Iic_inf_hom : inf_hom α (lower_set α)
⟨Iic, Iic_inf⟩
def
lower_set.Iic_inf_hom
order.upper_lower
src/order/upper_lower/hom.lean
[ "order.upper_lower.basic", "order.hom.complete_lattice" ]
[ "inf_hom", "lower_set" ]
`lower_set.Iic` as an `inf_hom`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_Iic_inf_hom : (Iic_inf_hom : α → lower_set α) = Iic
rfl
lemma
lower_set.coe_Iic_inf_hom
order.upper_lower
src/order/upper_lower/hom.lean
[ "order.upper_lower.basic", "order.hom.complete_lattice" ]
[ "lower_set" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Iic_inf_hom_apply (a : α) : Iic_inf_hom a = Iic a
rfl
lemma
lower_set.Iic_inf_hom_apply
order.upper_lower
src/order/upper_lower/hom.lean
[ "order.upper_lower.basic", "order.hom.complete_lattice" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Iic_Inf_hom : Inf_hom α (lower_set α)
⟨Iic, λ s, (Iic_Inf s).trans Inf_image.symm⟩
def
lower_set.Iic_Inf_hom
order.upper_lower
src/order/upper_lower/hom.lean
[ "order.upper_lower.basic", "order.hom.complete_lattice" ]
[ "Inf_hom", "lower_set" ]
`lower_set.Iic` as an `Inf_hom`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_Iic_Inf_hom : (Iic_Inf_hom : α → lower_set α) = Iic
rfl
lemma
lower_set.coe_Iic_Inf_hom
order.upper_lower
src/order/upper_lower/hom.lean
[ "order.upper_lower.basic", "order.hom.complete_lattice" ]
[ "lower_set" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Iic_Inf_hom_apply (a : α) : Iic_Inf_hom a = Iic a
rfl
lemma
lower_set.Iic_Inf_hom_apply
order.upper_lower
src/order/upper_lower/hom.lean
[ "order.upper_lower.basic", "order.hom.complete_lattice" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
finite.upper_closure [locally_finite_order_top α] (hs : s.finite) : (upper_closure s : set α).finite
by { rw coe_upper_closure, exact hs.bUnion (λ _ _, finite_Ici _) }
lemma
set.finite.upper_closure
order.upper_lower
src/order/upper_lower/locally_finite.lean
[ "order.locally_finite", "order.upper_lower.basic" ]
[ "coe_upper_closure", "finite", "locally_finite_order_top", "upper_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
finite.lower_closure [locally_finite_order_bot α] (hs : s.finite) : (lower_closure s : set α).finite
by { rw coe_lower_closure, exact hs.bUnion (λ _ _, finite_Iic _) }
lemma
set.finite.lower_closure
order.upper_lower
src/order/upper_lower/locally_finite.lean
[ "order.locally_finite", "order.upper_lower.basic" ]
[ "coe_lower_closure", "finite", "locally_finite_order_bot", "lower_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Indep_fun.indep_comap_natural_of_lt (hf : ∀ i, strongly_measurable (f i)) (hfi : Indep_fun (λ i, mβ) f μ) (hij : i < j) : indep (measurable_space.comap (f j) mβ) (filtration.natural f hf i) μ
begin suffices : indep (⨆ k ∈ {j}, measurable_space.comap (f k) mβ) (⨆ k ∈ {k | k ≤ i}, measurable_space.comap (f k) mβ) μ, { rwa supr_singleton at this }, exact indep_supr_of_disjoint (λ k, (hf k).measurable.comap_le) hfi (by simpa), end
lemma
probability_theory.Indep_fun.indep_comap_natural_of_lt
probability
src/probability/borel_cantelli.lean
[ "probability.martingale.borel_cantelli", "probability.conditional_expectation", "probability.independence.basic" ]
[ "measurable_space.comap", "supr_singleton" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Indep_fun.condexp_natural_ae_eq_of_lt [second_countable_topology β] [complete_space β] [normed_space ℝ β] (hf : ∀ i, strongly_measurable (f i)) (hfi : Indep_fun (λ i, mβ) f μ) (hij : i < j) : μ[f j | filtration.natural f hf i] =ᵐ[μ] λ ω, μ[f j]
condexp_indep_eq (hf j).measurable.comap_le (filtration.le _ _) (comap_measurable $ f j).strongly_measurable (hfi.indep_comap_natural_of_lt hf hij)
lemma
probability_theory.Indep_fun.condexp_natural_ae_eq_of_lt
probability
src/probability/borel_cantelli.lean
[ "probability.martingale.borel_cantelli", "probability.conditional_expectation", "probability.independence.basic" ]
[ "comap_measurable", "complete_space", "normed_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
Indep_set.condexp_indicator_filtration_of_set_ae_eq (hsm : ∀ n, measurable_set (s n)) (hs : Indep_set s μ) (hij : i < j) : μ[(s j).indicator (λ ω, 1 : Ω → ℝ) | filtration_of_set hsm i] =ᵐ[μ] λ ω, (μ (s j)).to_real
begin rw filtration.filtration_of_set_eq_natural hsm, refine (Indep_fun.condexp_natural_ae_eq_of_lt _ hs.Indep_fun_indicator hij).trans _, { simp only [integral_indicator_const _ (hsm _), algebra.id.smul_eq_mul, mul_one] }, { apply_instance } end
lemma
probability_theory.Indep_set.condexp_indicator_filtration_of_set_ae_eq
probability
src/probability/borel_cantelli.lean
[ "probability.martingale.borel_cantelli", "probability.conditional_expectation", "probability.independence.basic" ]
[ "algebra.id.smul_eq_mul", "measurable_set", "mul_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
measure_limsup_eq_one {s : ℕ → set Ω} (hsm : ∀ n, measurable_set (s n)) (hs : Indep_set s μ) (hs' : ∑' n, μ (s n) = ∞) : μ (limsup s at_top) = 1
begin rw measure_congr (eventually_eq_set.2 (ae_mem_limsup_at_top_iff μ $ measurable_set_filtration_of_set' hsm) : (limsup s at_top : set Ω) =ᵐ[μ] {ω | tendsto (λ n, ∑ k in finset.range n, μ[(s (k + 1)).indicator (1 : Ω → ℝ) | filtration_of_set hsm k] ω) at_top at_top}), suffices : {ω | tendsto (λ...
lemma
probability_theory.measure_limsup_eq_one
probability
src/probability/borel_cantelli.lean
[ "probability.martingale.borel_cantelli", "probability.conditional_expectation", "probability.independence.basic" ]
[ "ennreal.coe_ne_top", "ennreal.sum_lt_top", "ennreal.tendsto_nat_tsum", "ennreal.tendsto_nhds_top_iff_nnreal", "ennreal.to_real_le_to_real", "ennreal.to_real_nonneg", "ennreal.to_real_sum", "ennreal.tsum_add_one_eq_top", "finset.range", "measurable_set", "mem_upper_bounds", "monotone_nat_of_le...
**The second Borel-Cantelli lemma**: Given a sequence of independent sets `(sₙ)` such that `∑ n, μ sₙ = ∞`, `limsup sₙ` has measure 1.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
condexp_indep_eq (hle₁ : m₁ ≤ m) (hle₂ : m₂ ≤ m) [sigma_finite (μ.trim hle₂)] (hf : strongly_measurable[m₁] f) (hindp : indep m₁ m₂ μ) : μ[f | m₂] =ᵐ[μ] λ x, μ[f]
begin by_cases hfint : integrable f μ, swap, { rw [condexp_undef hfint, integral_undef hfint], refl, }, have hfint₁ := hfint.trim hle₁ hf, refine (ae_eq_condexp_of_forall_set_integral_eq hle₂ hfint (λ s _ hs, integrable_on_const.2 (or.inr hs)) (λ s hms hs, _) strongly_measurable_const.ae_strongly_measur...
lemma
measure_theory.condexp_indep_eq
probability
src/probability/conditional_expectation.lean
[ "probability.notation", "probability.independence.basic", "measure_theory.function.conditional_expectation.basic" ]
[ "coe_fn_coe_base", "continuous.const_smul", "continuous_linear_map.continuous", "ennreal.one_ne_top", "ennreal.to_real_mul", "is_closed_eq", "mul_comm", "set.inter_comm", "smul_add", "smul_smul", "submodule.coe_subtype", "submodule.coe_subtypeL'", "submodule.subtypeL" ]
If `m₁, m₂` are independent σ-algebras and `f` is `m₁`-measurable, then `𝔼[f | m₂] = 𝔼[f]` almost everywhere.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond (s : set Ω) : measure Ω
(μ s)⁻¹ • μ.restrict s
def
probability_theory.cond
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[]
The conditional probability measure of measure `μ` on set `s` is `μ` restricted to `s` and scaled by the inverse of `μ s` (to make it a probability measure): `(μ s)⁻¹ • μ.restrict s`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_is_probability_measure [is_finite_measure μ] (hcs : μ s ≠ 0) : is_probability_measure $ μ[|s]
⟨by { rw [cond, measure.smul_apply, measure.restrict_apply measurable_set.univ, set.univ_inter], exact ennreal.inv_mul_cancel hcs (measure_ne_top _ s) }⟩
lemma
probability_theory.cond_is_probability_measure
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[ "ennreal.inv_mul_cancel", "measurable_set.univ", "set.univ_inter" ]
The conditional probability measure of any finite measure on any set of positive measure is a probability measure.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_empty : μ[|∅] = 0
by simp [cond]
lemma
probability_theory.cond_empty
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_univ [is_probability_measure μ] : μ[|set.univ] = μ
by simp [cond, measure_univ, measure.restrict_univ]
lemma
probability_theory.cond_univ
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_apply (hms : measurable_set s) (t : set Ω) : μ[t|s] = (μ s)⁻¹ * μ (s ∩ t)
by { rw [cond, measure.smul_apply, measure.restrict_apply' hms, set.inter_comm], refl }
lemma
probability_theory.cond_apply
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[ "measurable_set", "set.inter_comm" ]
The axiomatic definition of conditional probability derived from a measure-theoretic one.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_inter_self (hms : measurable_set s) (t : set Ω) : μ[s ∩ t|s] = μ[t|s]
by rw [cond_apply _ hms, ← set.inter_assoc, set.inter_self, ← cond_apply _ hms]
lemma
probability_theory.cond_inter_self
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[ "measurable_set", "set.inter_assoc", "set.inter_self" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
inter_pos_of_cond_ne_zero (hms : measurable_set s) (hcst : μ[t|s] ≠ 0) : 0 < μ (s ∩ t)
begin refine pos_iff_ne_zero.mpr (right_ne_zero_of_mul _), { exact (μ s)⁻¹ }, convert hcst, simp [hms, set.inter_comm] end
lemma
probability_theory.inter_pos_of_cond_ne_zero
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[ "measurable_set", "right_ne_zero_of_mul", "set.inter_comm" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_pos_of_inter_ne_zero [is_finite_measure μ] (hms : measurable_set s) (hci : μ (s ∩ t) ≠ 0) : 0 < μ[|s] t
begin rw cond_apply _ hms, refine ennreal.mul_pos _ hci, exact ennreal.inv_ne_zero.mpr (measure_ne_top _ _), end
lemma
probability_theory.cond_pos_of_inter_ne_zero
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[ "ennreal.mul_pos", "measurable_set" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_cond_eq_cond_inter' (hms : measurable_set s) (hmt : measurable_set t) (hcs : μ s ≠ ∞) (hci : μ (s ∩ t) ≠ 0) : μ[|s][|t] = μ[|s ∩ t]
begin have hcs : μ s ≠ 0 := (μ.to_outer_measure.pos_of_subset_ne_zero (set.inter_subset_left _ _) hci).ne', ext u, simp [*, hms.inter hmt, cond_apply, ← mul_assoc, ← set.inter_assoc, ennreal.mul_inv, mul_comm, ← mul_assoc, ennreal.inv_mul_cancel], end
lemma
probability_theory.cond_cond_eq_cond_inter'
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[ "ennreal.inv_mul_cancel", "ennreal.mul_inv", "measurable_set", "mul_assoc", "mul_comm", "set.inter_assoc", "set.inter_subset_left" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_cond_eq_cond_inter [is_finite_measure μ] (hms : measurable_set s) (hmt : measurable_set t) (hci : μ (s ∩ t) ≠ 0) : μ[|s][|t] = μ[|s ∩ t]
cond_cond_eq_cond_inter' μ hms hmt (measure_ne_top μ s) hci
lemma
probability_theory.cond_cond_eq_cond_inter
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[ "measurable_set" ]
Conditioning first on `s` and then on `t` results in the same measure as conditioning on `s ∩ t`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_mul_eq_inter' (hms : measurable_set s) (hcs : μ s ≠ 0) (hcs' : μ s ≠ ∞) (t : set Ω) : μ[t|s] * μ s = μ (s ∩ t)
by rw [cond_apply μ hms t, mul_comm, ←mul_assoc, ennreal.mul_inv_cancel hcs hcs', one_mul]
lemma
probability_theory.cond_mul_eq_inter'
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[ "ennreal.mul_inv_cancel", "measurable_set", "mul_comm", "one_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_mul_eq_inter [is_finite_measure μ] (hms : measurable_set s) (hcs : μ s ≠ 0) (t : set Ω) : μ[t|s] * μ s = μ (s ∩ t)
cond_mul_eq_inter' μ hms hcs (measure_ne_top _ s) t
lemma
probability_theory.cond_mul_eq_inter
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[ "measurable_set" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_add_cond_compl_eq [is_finite_measure μ] (hms : measurable_set s) (hcs : μ s ≠ 0) (hcs' : μ sᶜ ≠ 0) : μ[t|s] * μ s + μ[t|sᶜ] * μ sᶜ = μ t
begin rw [cond_mul_eq_inter μ hms hcs, cond_mul_eq_inter μ hms.compl hcs', set.inter_comm _ t, set.inter_comm _ t], exact measure_inter_add_diff t hms, end
lemma
probability_theory.cond_add_cond_compl_eq
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[ "measurable_set", "set.inter_comm" ]
A version of the law of total probability.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_eq_inv_mul_cond_mul [is_finite_measure μ] (hms : measurable_set s) (hmt : measurable_set t) : μ[t|s] = (μ s)⁻¹ * μ[s|t] * (μ t)
begin by_cases ht : μ t = 0, { simp [cond, ht, measure.restrict_apply hmt, or.inr (measure_inter_null_of_null_left s ht)] }, { rw [mul_assoc, cond_mul_eq_inter μ hmt ht s, set.inter_comm, cond_apply _ hms] } end
theorem
probability_theory.cond_eq_inv_mul_cond_mul
probability
src/probability/conditional_probability.lean
[ "measure_theory.measure.measure_space" ]
[ "measurable_set", "mul_assoc", "set.inter_comm" ]
**Bayes' Theorem**
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count (s : set Ω) : measure Ω
measure.count[|s]
def
probability_theory.cond_count
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[]
Given a set `s`, `cond_count s` is the counting measure conditioned on `s`. In particular, `cond_count s t` is the proportion of `s` that is contained in `t`. This is a probability measure when `s` is finite and nonempty and is given by `probability_theory.cond_count_is_probability_measure`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_empty_meas : (cond_count ∅ : measure Ω) = 0
by simp [cond_count]
lemma
probability_theory.cond_count_empty_meas
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_empty {s : set Ω} : cond_count s ∅ = 0
by simp
lemma
probability_theory.cond_count_empty
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
finite_of_cond_count_ne_zero {s t : set Ω} (h : cond_count s t ≠ 0) : s.finite
begin by_contra hs', simpa [cond_count, cond, measure.count_apply_infinite hs'] using h, end
lemma
probability_theory.finite_of_cond_count_ne_zero
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "by_contra" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_univ [fintype Ω] {s : set Ω} : cond_count set.univ s = measure.count s / fintype.card Ω
begin rw [cond_count, cond_apply _ measurable_set.univ, ←ennreal.div_eq_inv_mul, set.univ_inter], congr', rw [←finset.coe_univ, measure.count_apply, finset.univ.tsum_subtype' (λ _, (1 : ennreal))], { simp [finset.card_univ] }, { exact (@finset.coe_univ Ω _).symm ▸ measurable_set.univ } end
lemma
probability_theory.cond_count_univ
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "ennreal", "finset.card_univ", "finset.coe_univ", "fintype", "fintype.card", "measurable_set.univ", "set.univ_inter" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_is_probability_measure {s : set Ω} (hs : s.finite) (hs' : s.nonempty) : is_probability_measure (cond_count s)
{ measure_univ := begin rw [cond_count, cond_apply _ hs.measurable_set, set.inter_univ, ennreal.inv_mul_cancel], { exact λ h, hs'.ne_empty $ measure.empty_of_count_eq_zero h }, { exact (measure.count_apply_lt_top.2 hs).ne } end }
lemma
probability_theory.cond_count_is_probability_measure
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "ennreal.inv_mul_cancel", "set.inter_univ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_singleton (ω : Ω) (t : set Ω) [decidable (ω ∈ t)] : cond_count {ω} t = if ω ∈ t then 1 else 0
begin rw [cond_count, cond_apply _ (measurable_set_singleton ω), measure.count_singleton, inv_one, one_mul], split_ifs, { rw [(by simpa : ({ω} : set Ω) ∩ t = {ω}), measure.count_singleton] }, { rw [(by simpa : ({ω} : set Ω) ∩ t = ∅), measure.count_empty] }, end
lemma
probability_theory.cond_count_singleton
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "inv_one", "one_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_inter_self (hs : s.finite): cond_count s (s ∩ t) = cond_count s t
by rw [cond_count, cond_inter_self _ hs.measurable_set]
lemma
probability_theory.cond_count_inter_self
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_self (hs : s.finite) (hs' : s.nonempty) : cond_count s s = 1
begin rw [cond_count, cond_apply _ hs.measurable_set, set.inter_self, ennreal.inv_mul_cancel], { exact λ h, hs'.ne_empty $ measure.empty_of_count_eq_zero h }, { exact (measure.count_apply_lt_top.2 hs).ne } end
lemma
probability_theory.cond_count_self
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "ennreal.inv_mul_cancel", "set.inter_self" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_eq_one_of (hs : s.finite) (hs' : s.nonempty) (ht : s ⊆ t) : cond_count s t = 1
begin haveI := cond_count_is_probability_measure hs hs', refine eq_of_le_of_not_lt prob_le_one _, rw [not_lt, ← cond_count_self hs hs'], exact measure_mono ht, end
lemma
probability_theory.cond_count_eq_one_of
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "eq_of_le_of_not_lt" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pred_true_of_cond_count_eq_one (h : cond_count s t = 1) : s ⊆ t
begin have hsf := finite_of_cond_count_ne_zero (by { rw h, exact one_ne_zero }), rw [cond_count, cond_apply _ hsf.measurable_set, mul_comm] at h, replace h := ennreal.eq_inv_of_mul_eq_one_left h, rw [inv_inv, measure.count_apply_finite _ hsf, measure.count_apply_finite _ (hsf.inter_of_left _), nat.cast_inj]...
lemma
probability_theory.pred_true_of_cond_count_eq_one
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "ennreal.eq_inv_of_mul_eq_one_left", "finset.eq_of_subset_of_card_le", "inv_inv", "mul_comm", "nat.cast_inj", "one_ne_zero", "set.finite.to_finset_inj" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_eq_zero_iff (hs : s.finite) : cond_count s t = 0 ↔ s ∩ t = ∅
by simp [cond_count, cond_apply _ hs.measurable_set, measure.count_apply_eq_top, set.not_infinite.2 hs, measure.count_apply_finite _ (hs.inter_of_left _)]
lemma
probability_theory.cond_count_eq_zero_iff
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_of_univ (hs : s.finite) (hs' : s.nonempty) : cond_count s set.univ = 1
cond_count_eq_one_of hs hs' s.subset_univ
lemma
probability_theory.cond_count_of_univ
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_inter (hs : s.finite) : cond_count s (t ∩ u) = cond_count (s ∩ t) u * cond_count s t
begin by_cases hst : s ∩ t = ∅, { rw [hst, cond_count_empty_meas, measure.coe_zero, pi.zero_apply, zero_mul, cond_count_eq_zero_iff hs, ← set.inter_assoc, hst, set.empty_inter] }, rw [cond_count, cond_count, cond_apply _ hs.measurable_set, cond_apply _ hs.measurable_set, cond_apply _ (hs.inter_of_left _...
lemma
probability_theory.cond_count_inter
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "ennreal.mul_inv_cancel", "measurable_set", "mul_assoc", "mul_comm", "one_mul", "set.empty_inter", "set.inter_assoc", "zero_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_inter' (hs : s.finite) : cond_count s (t ∩ u) = cond_count (s ∩ u) t * cond_count s u
begin rw ← set.inter_comm, exact cond_count_inter hs, end
lemma
probability_theory.cond_count_inter'
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "set.inter_comm" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_union (hs : s.finite) (htu : disjoint t u) : cond_count s (t ∪ u) = cond_count s t + cond_count s u
begin rw [cond_count, cond_apply _ hs.measurable_set, cond_apply _ hs.measurable_set, cond_apply _ hs.measurable_set, set.inter_union_distrib_left, measure_union, mul_add], exacts [htu.mono inf_le_right inf_le_right, (hs.inter_of_left _).measurable_set], end
lemma
probability_theory.cond_count_union
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "disjoint", "inf_le_right", "measurable_set", "set.inter_union_distrib_left" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_compl (t : set Ω) (hs : s.finite) (hs' : s.nonempty) : cond_count s t + cond_count s tᶜ = 1
begin rw [← cond_count_union hs disjoint_compl_right, set.union_compl_self, (cond_count_is_probability_measure hs hs').measure_univ], end
lemma
probability_theory.cond_count_compl
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "disjoint_compl_right", "set.union_compl_self" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_disjoint_union (hs : s.finite) (ht : t.finite) (hst : disjoint s t) : cond_count s u * cond_count (s ∪ t) s + cond_count t u * cond_count (s ∪ t) t = cond_count (s ∪ t) u
begin rcases s.eq_empty_or_nonempty with (rfl | hs'); rcases t.eq_empty_or_nonempty with (rfl | ht'), { simp }, { simp [cond_count_self ht ht'] }, { simp [cond_count_self hs hs'] }, rw [cond_count, cond_count, cond_count, cond_apply _ hs.measurable_set, cond_apply _ ht.measurable_set, cond_apply _ (hs.u...
lemma
probability_theory.cond_count_disjoint_union
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "disjoint", "ennreal.mul_inv_cancel", "inf_le_left", "measurable_set", "mul_assoc", "mul_comm", "one_mul", "set.union_inter_cancel_left", "set.union_inter_cancel_right", "set.union_inter_distrib_right" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cond_count_add_compl_eq (u t : set Ω) (hs : s.finite) : cond_count (s ∩ u) t * cond_count s u + cond_count (s ∩ uᶜ) t * cond_count s uᶜ = cond_count s t
begin conv_rhs { rw [(by simp : s = s ∩ u ∪ s ∩ uᶜ), ← cond_count_disjoint_union (hs.inter_of_left _) (hs.inter_of_left _) (disjoint_compl_right.mono inf_le_right inf_le_right)] }, simp [cond_count_inter_self hs], end
lemma
probability_theory.cond_count_add_compl_eq
probability
src/probability/cond_count.lean
[ "probability.conditional_probability" ]
[ "inf_le_right" ]
A version of the law of total probability for counting probabilites.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
has_pdf {m : measurable_space Ω} (X : Ω → E) (ℙ : measure Ω) (μ : measure E . volume_tac) : Prop
(pdf' : measurable X ∧ ∃ (f : E → ℝ≥0∞), measurable f ∧ map X ℙ = μ.with_density f)
class
measure_theory.has_pdf
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable", "measurable_space" ]
A random variable `X : Ω → E` is said to `has_pdf` with respect to the measure `ℙ` on `Ω` and `μ` on `E` if there exists a measurable function `f` such that the push-forward measure of `ℙ` along `X` equals `μ.with_density f`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
has_pdf.measurable {m : measurable_space Ω} (X : Ω → E) (ℙ : measure Ω) (μ : measure E . volume_tac) [hX : has_pdf X ℙ μ] : measurable X
hX.pdf'.1
lemma
measure_theory.has_pdf.measurable
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable", "measurable_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pdf {m : measurable_space Ω} (X : Ω → E) (ℙ : measure Ω) (μ : measure E . volume_tac)
if hX : has_pdf X ℙ μ then classical.some hX.pdf'.2 else 0
def
measure_theory.pdf
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable_space" ]
If `X` is a random variable that `has_pdf X ℙ μ`, then `pdf X` is the measurable function `f` such that the push-forward measure of `ℙ` along `X` equals `μ.with_density f`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pdf_undef {m : measurable_space Ω} {ℙ : measure Ω} {μ : measure E} {X : Ω → E} (h : ¬ has_pdf X ℙ μ) : pdf X ℙ μ = 0
by simp only [pdf, dif_neg h]
lemma
measure_theory.pdf_undef
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
has_pdf_of_pdf_ne_zero {m : measurable_space Ω} {ℙ : measure Ω} {μ : measure E} {X : Ω → E} (h : pdf X ℙ μ ≠ 0) : has_pdf X ℙ μ
begin by_contra hpdf, rw [pdf, dif_neg hpdf] at h, exact hpdf (false.rec (has_pdf X ℙ μ) (h rfl)) end
lemma
measure_theory.has_pdf_of_pdf_ne_zero
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "by_contra", "measurable_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pdf_eq_zero_of_not_measurable {m : measurable_space Ω} {ℙ : measure Ω} {μ : measure E} {X : Ω → E} (hX : ¬ measurable X) : pdf X ℙ μ = 0
pdf_undef (λ hpdf, hX hpdf.pdf'.1)
lemma
measure_theory.pdf_eq_zero_of_not_measurable
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable", "measurable_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
measurable_of_pdf_ne_zero {m : measurable_space Ω} {ℙ : measure Ω} {μ : measure E} (X : Ω → E) (h : pdf X ℙ μ ≠ 0) : measurable X
by { by_contra hX, exact h (pdf_eq_zero_of_not_measurable hX) }
lemma
measure_theory.measurable_of_pdf_ne_zero
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "by_contra", "measurable", "measurable_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
measurable_pdf {m : measurable_space Ω} (X : Ω → E) (ℙ : measure Ω) (μ : measure E . volume_tac) : measurable (pdf X ℙ μ)
begin by_cases hX : has_pdf X ℙ μ, { rw [pdf, dif_pos hX], exact (classical.some_spec hX.pdf'.2).1 }, { rw [pdf, dif_neg hX], exact measurable_zero } end
lemma
measure_theory.measurable_pdf
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable", "measurable_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_eq_with_density_pdf {m : measurable_space Ω} (X : Ω → E) (ℙ : measure Ω) (μ : measure E . volume_tac) [hX : has_pdf X ℙ μ] : measure.map X ℙ = μ.with_density (pdf X ℙ μ)
begin rw [pdf, dif_pos hX], exact (classical.some_spec hX.pdf'.2).2 end
lemma
measure_theory.map_eq_with_density_pdf
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_eq_set_lintegral_pdf {m : measurable_space Ω} (X : Ω → E) (ℙ : measure Ω) (μ : measure E . volume_tac) [hX : has_pdf X ℙ μ] {s : set E} (hs : measurable_set s) : measure.map X ℙ s = ∫⁻ x in s, pdf X ℙ μ x ∂μ
by rw [← with_density_apply _ hs, map_eq_with_density_pdf X ℙ μ]
lemma
measure_theory.map_eq_set_lintegral_pdf
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable_set", "measurable_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
lintegral_eq_measure_univ {X : Ω → E} [has_pdf X ℙ μ] : ∫⁻ x, pdf X ℙ μ x ∂μ = ℙ set.univ
begin rw [← set_lintegral_univ, ← map_eq_set_lintegral_pdf X ℙ μ measurable_set.univ, measure.map_apply (has_pdf.measurable X ℙ μ) measurable_set.univ, set.preimage_univ], end
lemma
measure_theory.pdf.lintegral_eq_measure_univ
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable_set.univ", "set.preimage_univ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ae_lt_top [is_finite_measure ℙ] {μ : measure E} {X : Ω → E} : ∀ᵐ x ∂μ, pdf X ℙ μ x < ∞
begin by_cases hpdf : has_pdf X ℙ μ, { haveI := hpdf, refine ae_lt_top (measurable_pdf X ℙ μ) _, rw lintegral_eq_measure_univ, exact (measure_lt_top _ _).ne }, { rw [pdf, dif_neg hpdf], exact filter.eventually_of_forall (λ x, with_top.zero_lt_top) } end
lemma
measure_theory.pdf.ae_lt_top
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "filter.eventually_of_forall", "with_top.zero_lt_top" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
of_real_to_real_ae_eq [is_finite_measure ℙ] {X : Ω → E} : (λ x, ennreal.of_real (pdf X ℙ μ x).to_real) =ᵐ[μ] pdf X ℙ μ
of_real_to_real_ae_eq ae_lt_top
lemma
measure_theory.pdf.of_real_to_real_ae_eq
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "ennreal.of_real" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
integrable_iff_integrable_mul_pdf [is_finite_measure ℙ] {X : Ω → E} [has_pdf X ℙ μ] {f : E → ℝ} (hf : measurable f) : integrable (λ x, f (X x)) ℙ ↔ integrable (λ x, f x * (pdf X ℙ μ x).to_real) μ
begin rw [← integrable_map_measure hf.ae_strongly_measurable (has_pdf.measurable X ℙ μ).ae_measurable, map_eq_with_density_pdf X ℙ μ, integrable_with_density_iff (measurable_pdf _ _ _) ae_lt_top], apply_instance end
lemma
measure_theory.pdf.integrable_iff_integrable_mul_pdf
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "ae_measurable", "measurable" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
integral_fun_mul_eq_integral [is_finite_measure ℙ] {X : Ω → E} [has_pdf X ℙ μ] {f : E → ℝ} (hf : measurable f) : ∫ x, f x * (pdf X ℙ μ x).to_real ∂μ = ∫ x, f (X x) ∂ℙ
begin by_cases hpdf : integrable (λ x, f x * (pdf X ℙ μ x).to_real) μ, { rw [← integral_map (has_pdf.measurable X ℙ μ).ae_measurable hf.ae_strongly_measurable, map_eq_with_density_pdf X ℙ μ, integral_eq_lintegral_pos_part_sub_lintegral_neg_part hpdf, integral_eq_lintegral_pos_part_sub_linteg...
lemma
measure_theory.pdf.integral_fun_mul_eq_integral
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "ae_measurable", "ennreal.coe_mul", "ennreal.of_real", "ennreal.of_real_mul", "ennreal.to_real_nonneg", "filter.eventually_eq.mul", "measurable", "mul_comm", "neg_mul_eq_neg_mul", "nnnorm_smul", "real.ennnorm_eq_of_real", "smul_eq_mul" ]
**The Law of the Unconscious Statistician**: Given a random variable `X` and a measurable function `f`, `f ∘ X` is a random variable with expectation `∫ x, f x * pdf X ∂μ` where `μ` is a measure on the codomain of `X`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_absolutely_continuous {X : Ω → E} [has_pdf X ℙ μ] : map X ℙ ≪ μ
by { rw map_eq_with_density_pdf X ℙ μ, exact with_density_absolutely_continuous _ _, }
lemma
measure_theory.pdf.map_absolutely_continuous
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_quasi_measure_preserving {X : Ω → E} [has_pdf X ℙ μ] : quasi_measure_preserving X ℙ μ
{ measurable := has_pdf.measurable X ℙ μ, absolutely_continuous := map_absolutely_continuous, }
lemma
measure_theory.pdf.to_quasi_measure_preserving
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable" ]
A random variable that `has_pdf` is quasi-measure preserving.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
have_lebesgue_decomposition_of_has_pdf {X : Ω → E} [hX' : has_pdf X ℙ μ] : (map X ℙ).have_lebesgue_decomposition μ
⟨⟨⟨0, pdf X ℙ μ⟩, by simp only [zero_add, measurable_pdf X ℙ μ, true_and, mutually_singular.zero_left, map_eq_with_density_pdf X ℙ μ] ⟩⟩
lemma
measure_theory.pdf.have_lebesgue_decomposition_of_has_pdf
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
has_pdf_iff {X : Ω → E} : has_pdf X ℙ μ ↔ measurable X ∧ (map X ℙ).have_lebesgue_decomposition μ ∧ map X ℙ ≪ μ
begin split, { intro hX', exactI ⟨hX'.pdf'.1, have_lebesgue_decomposition_of_has_pdf, map_absolutely_continuous⟩ }, { rintros ⟨hX, h_decomp, h⟩, haveI := h_decomp, refine ⟨⟨hX, (measure.map X ℙ).rn_deriv μ, measurable_rn_deriv _ _, _⟩⟩, rwa with_density_rn_deriv_eq } end
lemma
measure_theory.pdf.has_pdf_iff
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
has_pdf_iff_of_measurable {X : Ω → E} (hX : measurable X) : has_pdf X ℙ μ ↔ (map X ℙ).have_lebesgue_decomposition μ ∧ map X ℙ ≪ μ
by { rw has_pdf_iff, simp only [hX, true_and], }
lemma
measure_theory.pdf.has_pdf_iff_of_measurable
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quasi_measure_preserving_has_pdf {X : Ω → E} [has_pdf X ℙ μ] {g : E → F} (hg : quasi_measure_preserving g μ ν) (hmap : (map g (map X ℙ)).have_lebesgue_decomposition ν) : has_pdf (g ∘ X) ℙ ν
begin rw [has_pdf_iff, ← map_map hg.measurable (has_pdf.measurable X ℙ μ)], refine ⟨hg.measurable.comp (has_pdf.measurable X ℙ μ), hmap, _⟩, rw [map_eq_with_density_pdf X ℙ μ], refine absolutely_continuous.mk (λ s hsm hs, _), rw [map_apply hg.measurable hsm, with_density_apply _ (hg.measurable hsm)], have :...
lemma
measure_theory.pdf.quasi_measure_preserving_has_pdf
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[]
A random variable that `has_pdf` transformed under a `quasi_measure_preserving` map also `has_pdf` if `(map g (map X ℙ)).have_lebesgue_decomposition μ`. `quasi_measure_preserving_has_pdf'` is more useful in the case we are working with a probability measure and a real-valued random variable.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
quasi_measure_preserving_has_pdf' [is_finite_measure ℙ] [sigma_finite ν] {X : Ω → E} [has_pdf X ℙ μ] {g : E → F} (hg : quasi_measure_preserving g μ ν) : has_pdf (g ∘ X) ℙ ν
quasi_measure_preserving_has_pdf hg infer_instance
lemma
measure_theory.pdf.quasi_measure_preserving_has_pdf'
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
real.has_pdf_iff_of_measurable (hX : measurable X) : has_pdf X ℙ ↔ map X ℙ ≪ volume
begin rw [has_pdf_iff_of_measurable hX, and_iff_right_iff_imp], exact λ h, infer_instance, end
lemma
measure_theory.pdf.real.has_pdf_iff_of_measurable
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "and_iff_right_iff_imp", "measurable" ]
A real-valued random variable `X` `has_pdf X ℙ λ` (where `λ` is the Lebesgue measure) if and only if the push-forward measure of `ℙ` along `X` is absolutely continuous with respect to `λ`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
real.has_pdf_iff : has_pdf X ℙ ↔ measurable X ∧ map X ℙ ≪ volume
begin by_cases hX : measurable X, { rw [real.has_pdf_iff_of_measurable hX, iff_and_self], exact λ h, hX, apply_instance }, { exact ⟨λ h, false.elim (hX h.pdf'.1), λ h, false.elim (hX h.1)⟩, } end
lemma
measure_theory.pdf.real.has_pdf_iff
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "iff_and_self", "measurable" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
integral_mul_eq_integral [has_pdf X ℙ] : ∫ x, x * (pdf X ℙ volume x).to_real = ∫ x, X x ∂ℙ
integral_fun_mul_eq_integral measurable_id
lemma
measure_theory.pdf.integral_mul_eq_integral
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable_id" ]
If `X` is a real-valued random variable that has pdf `f`, then the expectation of `X` equals `∫ x, x * f x ∂λ` where `λ` is the Lebesgue measure.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
has_finite_integral_mul {f : ℝ → ℝ} {g : ℝ → ℝ≥0∞} (hg : pdf X ℙ =ᵐ[volume] g) (hgi : ∫⁻ x, ‖f x‖₊ * g x ≠ ∞) : has_finite_integral (λ x, f x * (pdf X ℙ volume x).to_real)
begin rw has_finite_integral, have : (λ x, ↑‖f x‖₊ * g x) =ᵐ[volume] (λ x, ‖f x * (pdf X ℙ volume x).to_real‖₊), { refine ae_eq_trans (filter.eventually_eq.mul (ae_eq_refl (λ x, ‖f x‖₊)) (ae_eq_trans hg.symm of_real_to_real_ae_eq.symm)) _, simp_rw [← smul_eq_mul, nnnorm_smul, ennreal.coe_mul, smul_eq_mu...
lemma
measure_theory.pdf.has_finite_integral_mul
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "ennreal.coe_mul", "ennreal.to_real_nonneg", "filter.eventually_eq.mul", "lt_top_iff_ne_top", "nnnorm_smul", "real.ennnorm_eq_of_real", "smul_eq_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_uniform {m : measurable_space Ω} (X : Ω → E) (support : set E) (ℙ : measure Ω) (μ : measure E . volume_tac)
pdf X ℙ μ =ᵐ[μ] support.indicator ((μ support)⁻¹ • 1)
def
measure_theory.pdf.is_uniform
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "measurable_space" ]
A random variable `X` has uniform distribution if it has a probability density function `f` with support `s` such that `f = (μ s)⁻¹ 1ₛ` a.e. where `1ₛ` is the indicator function for `s`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
has_pdf {m : measurable_space Ω} {X : Ω → E} {ℙ : measure Ω} {μ : measure E} {s : set E} (hns : μ s ≠ 0) (hnt : μ s ≠ ∞) (hu : is_uniform X s ℙ μ) : has_pdf X ℙ μ
has_pdf_of_pdf_ne_zero begin intro hpdf, rw [is_uniform, hpdf] at hu, suffices : μ (s ∩ function.support ((μ s)⁻¹ • 1)) = 0, { have heq : function.support ((μ s)⁻¹ • (1 : E → ℝ≥0∞)) = set.univ, { ext x, rw [function.mem_support], simp [hnt] }, rw [heq, set.inter_univ] at this, exact hns ...
lemma
measure_theory.pdf.is_uniform.has_pdf
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "function.support", "measurable_space", "set.inter_univ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pdf_to_real_ae_eq {m : measurable_space Ω} {X : Ω → E} {ℙ : measure Ω} {μ : measure E} {s : set E} (hX : is_uniform X s ℙ μ) : (λ x, (pdf X ℙ μ x).to_real) =ᵐ[μ] (λ x, (s.indicator ((μ s)⁻¹ • (1 : E → ℝ≥0∞)) x).to_real)
filter.eventually_eq.fun_comp hX ennreal.to_real
lemma
measure_theory.pdf.is_uniform.pdf_to_real_ae_eq
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "ennreal.to_real", "filter.eventually_eq.fun_comp", "measurable_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
measure_preimage {m : measurable_space Ω} {X : Ω → E} {ℙ : measure Ω} {μ : measure E} {s : set E} (hns : μ s ≠ 0) (hnt : μ s ≠ ∞) (hms : measurable_set s) (hu : is_uniform X s ℙ μ) {A : set E} (hA : measurable_set A) : ℙ (X ⁻¹' A) = μ (s ∩ A) / μ s
begin haveI := hu.has_pdf hns hnt, rw [←measure.map_apply (has_pdf.measurable X ℙ μ) hA, map_eq_set_lintegral_pdf X ℙ μ hA, lintegral_congr_ae hu.restrict], simp only [hms, hA, lintegral_indicator, pi.smul_apply, pi.one_apply, algebra.id.smul_eq_mul, mul_one, lintegral_const, restrict_apply', set.univ_int...
lemma
measure_theory.pdf.is_uniform.measure_preimage
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "algebra.id.smul_eq_mul", "ennreal.div_eq_inv_mul", "measurable_set", "measurable_space", "mul_one", "pi.one_apply", "pi.smul_apply", "set.univ_inter" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_probability_measure {m : measurable_space Ω} {X : Ω → E} {ℙ : measure Ω} {μ : measure E} {s : set E} (hns : μ s ≠ 0) (hnt : μ s ≠ ∞) (hms : measurable_set s) (hu : is_uniform X s ℙ μ) : is_probability_measure ℙ
⟨begin have : X ⁻¹' set.univ = set.univ, { simp only [set.preimage_univ] }, rw [←this, hu.measure_preimage hns hnt hms measurable_set.univ, set.inter_univ, ennreal.div_self hns hnt], end⟩
lemma
measure_theory.pdf.is_uniform.is_probability_measure
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "ennreal.div_self", "measurable_set", "measurable_set.univ", "measurable_space", "set.inter_univ", "set.preimage_univ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_pdf_integrable [is_finite_measure ℙ] (hcs : is_compact s) (huX : is_uniform X s ℙ) : integrable (λ x : ℝ, x * (pdf X ℙ volume x).to_real)
begin by_cases hsupp : volume s = ∞, { have : pdf X ℙ =ᵐ[volume] 0, { refine ae_eq_trans huX _, simp [hsupp] }, refine integrable.congr (integrable_zero _ _ _) _, rw [(by simp : (λ x, 0 : ℝ → ℝ) = (λ x, x * (0 : ℝ≥0∞).to_real))], refine filter.eventually_eq.mul (ae_eq_refl _) (filter.eve...
lemma
measure_theory.pdf.is_uniform.mul_pdf_integrable
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "algebra.id.smul_eq_mul", "ennreal.mul_lt_top", "ennreal.to_real", "filter.eventually_eq.fun_comp", "filter.eventually_eq.mul", "is_compact", "mul_one", "pi.one_apply", "pi.smul_apply" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
integral_eq (hnt : volume s ≠ ∞) (huX : is_uniform X s ℙ) : ∫ x, X x ∂ℙ = (volume s)⁻¹.to_real * ∫ x in s, x
begin haveI := has_pdf hns hnt huX, haveI := huX.is_probability_measure hns hnt hms, rw ← integral_mul_eq_integral, rw integral_congr_ae (filter.eventually_eq.mul (ae_eq_refl _) (pdf_to_real_ae_eq huX)), have : ∀ x, x * (s.indicator ((volume s)⁻¹ • (1 : ℝ → ℝ≥0∞)) x).to_real = x * (s.indicator ((volume s)...
lemma
measure_theory.pdf.is_uniform.integral_eq
probability
src/probability/density.lean
[ "measure_theory.decomposition.radon_nikodym", "measure_theory.measure.haar.of_basis" ]
[ "algebra.id.smul_eq_mul", "filter.eventually_eq.mul", "mul_comm", "mul_one" ]
A real uniform random variable `X` with support `s` has expectation `(λ s)⁻¹ * ∫ x in s, x ∂λ` where `λ` is the Lebesgue measure.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ident_distrib (f : α → γ) (g : β → γ) (μ : measure α . volume_tac) (ν : measure β . volume_tac) : Prop
(ae_measurable_fst : ae_measurable f μ) (ae_measurable_snd : ae_measurable g ν) (map_eq : measure.map f μ = measure.map g ν)
structure
probability_theory.ident_distrib
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "ae_measurable", "map_eq" ]
Two functions defined on two (possibly different) measure spaces are identically distributed if their image measures coincide. This only makes sense when the functions are ae measurable (as otherwise the image measures are not defined), so we require this as well in the definition.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
refl (hf : ae_measurable f μ) : ident_distrib f f μ μ
{ ae_measurable_fst := hf, ae_measurable_snd := hf, map_eq := rfl }
lemma
probability_theory.ident_distrib.refl
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "ae_measurable", "map_eq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
symm (h : ident_distrib f g μ ν) : ident_distrib g f ν μ
{ ae_measurable_fst := h.ae_measurable_snd, ae_measurable_snd := h.ae_measurable_fst, map_eq := h.map_eq.symm }
lemma
probability_theory.ident_distrib.symm
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "map_eq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
trans {ρ : measure δ} {h : δ → γ} (h₁ : ident_distrib f g μ ν) (h₂ : ident_distrib g h ν ρ) : ident_distrib f h μ ρ
{ ae_measurable_fst := h₁.ae_measurable_fst, ae_measurable_snd := h₂.ae_measurable_snd, map_eq := h₁.map_eq.trans h₂.map_eq }
lemma
probability_theory.ident_distrib.trans
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "map_eq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp_of_ae_measurable {u : γ → δ} (h : ident_distrib f g μ ν) (hu : ae_measurable u (measure.map f μ)) : ident_distrib (u ∘ f) (u ∘ g) μ ν
{ ae_measurable_fst := hu.comp_ae_measurable h.ae_measurable_fst, ae_measurable_snd := by { rw h.map_eq at hu, exact hu.comp_ae_measurable h.ae_measurable_snd }, map_eq := begin rw [← ae_measurable.map_map_of_ae_measurable hu h.ae_measurable_fst, ← ae_measurable.map_map_of_ae_measurable _ h.ae_measu...
lemma
probability_theory.ident_distrib.comp_of_ae_measurable
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "ae_measurable", "ae_measurable.map_map_of_ae_measurable", "map_eq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
comp {u : γ → δ} (h : ident_distrib f g μ ν) (hu : measurable u) : ident_distrib (u ∘ f) (u ∘ g) μ ν
h.comp_of_ae_measurable hu.ae_measurable
lemma
probability_theory.ident_distrib.comp
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "measurable" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
of_ae_eq {g : α → γ} (hf : ae_measurable f μ) (heq : f =ᵐ[μ] g) : ident_distrib f g μ μ
{ ae_measurable_fst := hf, ae_measurable_snd := hf.congr heq, map_eq := measure.map_congr heq }
lemma
probability_theory.ident_distrib.of_ae_eq
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "ae_measurable", "map_eq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
measure_mem_eq (h : ident_distrib f g μ ν) {s : set γ} (hs : measurable_set s) : μ (f ⁻¹' s) = ν (g ⁻¹' s)
by rw [← measure.map_apply_of_ae_measurable h.ae_measurable_fst hs, ← measure.map_apply_of_ae_measurable h.ae_measurable_snd hs, h.map_eq]
lemma
probability_theory.ident_distrib.measure_mem_eq
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "measurable_set" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ae_snd (h : ident_distrib f g μ ν) {p : γ → Prop} (pmeas : measurable_set {x | p x}) (hp : ∀ᵐ x ∂μ, p (f x)) : ∀ᵐ x ∂ν, p (g x)
begin apply (ae_map_iff h.ae_measurable_snd pmeas).1, rw ← h.map_eq, exact (ae_map_iff h.ae_measurable_fst pmeas).2 hp, end
lemma
probability_theory.ident_distrib.ae_snd
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "measurable_set" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ae_mem_snd (h : ident_distrib f g μ ν) {t : set γ} (tmeas : measurable_set t) (ht : ∀ᵐ x ∂μ, f x ∈ t) : ∀ᵐ x ∂ν, g x ∈ t
h.ae_snd tmeas ht
lemma
probability_theory.ident_distrib.ae_mem_snd
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "measurable_set" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ae_strongly_measurable_fst [topological_space γ] [metrizable_space γ] [opens_measurable_space γ] [second_countable_topology γ] (h : ident_distrib f g μ ν) : ae_strongly_measurable f μ
h.ae_measurable_fst.ae_strongly_measurable
lemma
probability_theory.ident_distrib.ae_strongly_measurable_fst
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "opens_measurable_space", "topological_space" ]
In a second countable topology, the first function in an identically distributed pair is a.e. strongly measurable. So is the second function, but use `h.symm.ae_strongly_measurable_fst` as `h.ae_strongly_measurable_snd` has a different meaning.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ae_strongly_measurable_snd [topological_space γ] [metrizable_space γ] [borel_space γ] (h : ident_distrib f g μ ν) (hf : ae_strongly_measurable f μ) : ae_strongly_measurable g ν
begin refine ae_strongly_measurable_iff_ae_measurable_separable.2 ⟨h.ae_measurable_snd, _⟩, rcases (ae_strongly_measurable_iff_ae_measurable_separable.1 hf).2 with ⟨t, t_sep, ht⟩, refine ⟨closure t, t_sep.closure, _⟩, apply h.ae_mem_snd is_closed_closure.measurable_set, filter_upwards [ht] with x hx using sub...
lemma
probability_theory.ident_distrib.ae_strongly_measurable_snd
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "borel_space", "subset_closure", "topological_space" ]
If `f` and `g` are identically distributed and `f` is a.e. strongly measurable, so is `g`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ae_strongly_measurable_iff [topological_space γ] [metrizable_space γ] [borel_space γ] (h : ident_distrib f g μ ν) : ae_strongly_measurable f μ ↔ ae_strongly_measurable g ν
⟨λ hf, h.ae_strongly_measurable_snd hf, λ hg, h.symm.ae_strongly_measurable_snd hg⟩
lemma
probability_theory.ident_distrib.ae_strongly_measurable_iff
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "borel_space", "topological_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ess_sup_eq [conditionally_complete_linear_order γ] [topological_space γ] [opens_measurable_space γ] [order_closed_topology γ] (h : ident_distrib f g μ ν) : ess_sup f μ = ess_sup g ν
begin have I : ∀ a, μ {x : α | a < f x} = ν {x : β | a < g x} := λ a, h.measure_mem_eq measurable_set_Ioi, simp_rw [ess_sup_eq_Inf, I], end
lemma
probability_theory.ident_distrib.ess_sup_eq
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "conditionally_complete_linear_order", "ess_sup", "ess_sup_eq_Inf", "measurable_set_Ioi", "opens_measurable_space", "order_closed_topology", "topological_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
lintegral_eq {f : α → ℝ≥0∞} {g : β → ℝ≥0∞} (h : ident_distrib f g μ ν) : ∫⁻ x, f x ∂μ = ∫⁻ x, g x ∂ν
begin change ∫⁻ x, id (f x) ∂μ = ∫⁻ x, id (g x) ∂ν, rw [← lintegral_map' ae_measurable_id h.ae_measurable_fst, ← lintegral_map' ae_measurable_id h.ae_measurable_snd, h.map_eq], end
lemma
probability_theory.ident_distrib.lintegral_eq
probability
src/probability/ident_distrib.lean
[ "probability.variance", "measure_theory.function.uniform_integrable" ]
[ "ae_measurable_id" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83