mathlib documentation

data.real.nnreal

Nonnegative real numbers #

In this file we define nnreal (notation: ℝ≥0) to be the type of non-negative real numbers, a.k.a. the interval [0, ∞). We also define the following operations and structures on ℝ≥0:

We also define an instance can_lift ℝ ℝ≥0. This instance can be used by the lift tactic to replace x : ℝ and hx : 0 ≤ x in the proof context with x : ℝ≥0 while replacing all occurences of x with ↑x. This tactic also works for a function f : α → ℝ with a hypothesis hf : ∀ x, 0 ≤ f x.

Notations #

This file defines ℝ≥0 as a localized notation for nnreal.

TODO #

semifield instance

@[protected, instance]
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noncomputable def nnreal.has_sub  :
@[protected, instance]
@[protected, instance]
def nnreal  :
Type

Nonnegative real numbers.

Equations
Instances for nnreal
@[protected, instance]
noncomputable def nnreal.has_div  :
@[protected, instance]
Equations
@[simp]
theorem nnreal.val_eq_coe (n : nnreal) :
n.val = ↑n
@[protected, instance]
Equations
@[protected]
theorem nnreal.eq {n m : nnreal} :
↑n = ↑m → n = m
@[protected]
theorem nnreal.eq_iff {n m : nnreal} :
↑n = ↑m ↔ n = m
theorem nnreal.ne_iff {x y : nnreal} :
↑x ≠ ↑y ↔ x ≠ y
@[protected]
theorem nnreal.forall {p : nnreal → Prop} :
(∀ (x : nnreal), p x) ↔ ∀ (x : ℝ) (hx : 0 ≤ x), p ⟨x, hx⟩
@[protected]
theorem nnreal.exists {p : nnreal → Prop} :
(∃ (x : nnreal), p x) ↔ ∃ (x : ℝ) (hx : 0 ≤ x), p ⟨x, hx⟩
noncomputable def real.to_nnreal (r : ℝ) :

Reinterpret a real number r as a non-negative real number. Returns 0 if r < 0.

Equations
theorem real.coe_to_nnreal (r : ℝ) (hr : 0 ≤ r) :
theorem nnreal.coe_nonneg (r : nnreal) :
0 ≤ ↑r
@[norm_cast]
theorem nnreal.coe_mk (a : ℝ) (ha : 0 ≤ a) :
↑⟨a, ha⟩ = a
@[protected, simp, norm_cast]
theorem nnreal.coe_eq {r₁ r₂ : nnreal} :
↑r₁ = ↑r₂ ↔ r₁ = r₂
@[protected]
theorem nnreal.coe_zero  :
↑0 = 0
@[protected]
theorem nnreal.coe_one  :
↑1 = 1
@[protected]
theorem nnreal.coe_add (r₁ r₂ : nnreal) :
↑(r₁ + r₂) = ↑r₁ + ↑r₂
@[protected]
theorem nnreal.coe_mul (r₁ r₂ : nnreal) :
↑(r₁ * r₂) = ↑r₁ * ↑r₂
@[protected]
theorem nnreal.coe_inv (r : nnreal) :
@[protected]
theorem nnreal.coe_div (r₁ r₂ : nnreal) :
↑(r₁ / r₂) = ↑r₁ / ↑r₂
@[protected, simp, norm_cast]
theorem nnreal.coe_bit0 (r : nnreal) :
@[protected, simp, norm_cast]
theorem nnreal.coe_bit1 (r : nnreal) :
@[protected]
theorem nnreal.coe_two  :
↑2 = 2
@[protected, simp, norm_cast]
theorem nnreal.coe_sub {r₁ r₂ : nnreal} (h : r₂ ≤ r₁) :
↑(r₁ - r₂) = ↑r₁ - ↑r₂
@[protected, simp, norm_cast]
theorem nnreal.coe_eq_zero (r : nnreal) :
↑r = 0 ↔ r = 0
@[protected, simp, norm_cast]
theorem nnreal.coe_eq_one (r : nnreal) :
↑r = 1 ↔ r = 1
theorem nnreal.coe_ne_zero {r : nnreal} :
↑r ≠ 0 ↔ r ≠ 0
@[protected, instance]
def nnreal.mul_action {M : Type u_1} [mul_action ℝ M] :

A mul_action over ℝ restricts to a mul_action over ℝ≥0.

Equations
theorem nnreal.smul_def {M : Type u_1} [mul_action ℝ M] (c : nnreal) (x : M) :
c • x = ↑c • x
@[protected, instance]
def nnreal.is_scalar_tower {M : Type u_1} {N : Type u_2} [mul_action ℝ M] [mul_action ℝ N] [has_smul M N] [is_scalar_tower ℝ M N] :
@[protected, instance]
def nnreal.smul_comm_class_left {M : Type u_1} {N : Type u_2} [mul_action ℝ N] [has_smul M N] [smul_comm_class ℝ M N] :
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def nnreal.smul_comm_class_right {M : Type u_1} {N : Type u_2} [mul_action ℝ N] [has_smul M N] [smul_comm_class M ℝ N] :
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def nnreal.module {M : Type u_1} [add_comm_monoid M] [module ℝ M] :

A module over ℝ restricts to a module over ℝ≥0.

Equations
@[protected, instance]
def nnreal.algebra {A : Type u_1} [semiring A] [algebra ℝ A] :

An algebra over ℝ restricts to an algebra over ℝ≥0.

Equations
@[simp, norm_cast]
theorem nnreal.coe_indicator {α : Type u_1} (s : set α) (f : α → nnreal) (a : α) :
↑(s.indicator f a) = s.indicator (λ (x : α), ↑(f x)) a
@[simp, norm_cast]
theorem nnreal.coe_pow (r : nnreal) (n : ℕ) :
↑(r ^ n) = ↑r ^ n
@[simp, norm_cast]
theorem nnreal.coe_zpow (r : nnreal) (n : ℤ) :
↑(r ^ n) = ↑r ^ n
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theorem nnreal.coe_list_sum (l : list nnreal) :
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theorem nnreal.coe_sum {α : Type u_1} {s : finset α} {f : α → nnreal} :
↑(s.sum (λ (a : α), f a)) = s.sum (λ (a : α), ↑(f a))
theorem real.to_nnreal_sum_of_nonneg {α : Type u_1} {s : finset α} {f : α → ℝ} (hf : ∀ (a : α), a ∈ s → 0 ≤ f a) :
(s.sum (λ (a : α), f a)).to_nnreal = s.sum (λ (a : α), (f a).to_nnreal)
@[norm_cast]
theorem nnreal.coe_prod {α : Type u_1} {s : finset α} {f : α → nnreal} :
↑(s.prod (λ (a : α), f a)) = s.prod (λ (a : α), ↑(f a))
theorem real.to_nnreal_prod_of_nonneg {α : Type u_1} {s : finset α} {f : α → ℝ} (hf : ∀ (a : α), a ∈ s → 0 ≤ f a) :
(s.prod (λ (a : α), f a)).to_nnreal = s.prod (λ (a : α), (f a).to_nnreal)
theorem nnreal.nsmul_coe (r : nnreal) (n : ℕ) :
↑(n • r) = n • ↑r
@[protected, simp, norm_cast]
theorem nnreal.coe_nat_cast (n : ℕ) :
@[protected, simp, norm_cast]
theorem nnreal.coe_le_coe {r₁ r₂ : nnreal} :
↑r₁ ≤ ↑r₂ ↔ r₁ ≤ r₂
@[protected, simp, norm_cast]
theorem nnreal.coe_lt_coe {r₁ r₂ : nnreal} :
↑r₁ < ↑r₂ ↔ r₁ < r₂
@[protected, simp, norm_cast]
theorem nnreal.coe_pos {r : nnreal} :
0 < ↑r ↔ 0 < r
@[protected]
@[simp]
theorem real.to_nnreal_coe {r : nnreal} :
@[simp]
theorem nnreal.mk_coe_nat (n : ℕ) :
⟨↑n, _⟩ = ↑n
@[simp]

real.to_nnreal and coe : ℝ≥0 → ℝ form a Galois insertion.

Equations
@[simp]
theorem nnreal.order_iso_Icc_zero_coe_apply_coe_coe (a : nnreal) (ᾰ : {x // set.Ici 0 x ∧ (λ (x : ℝ), x ≤ ↑a) x}) :

If a is a nonnegative real number, then the closed interval [0, a] in ℝ is order isomorphic to the interval set.Iic a.

Equations
theorem nnreal.coe_image {s : set nnreal} :
coe '' s = {x : ℝ | ∃ (h : 0 ≤ x), ⟨x, h⟩ ∈ s}
@[norm_cast]
@[norm_cast]
theorem nnreal.coe_supr {ι : Sort u_1} (s : ι → nnreal) :
(↑⨆ (i : ι), s i) = ⨆ (i : ι), ↑(s i)
@[norm_cast]
@[simp]
@[norm_cast]
theorem nnreal.coe_infi {ι : Sort u_1} (s : ι → nnreal) :
(↑⨅ (i : ι), s i) = ⨅ (i : ι), ↑(s i)
theorem nnreal.le_infi_add_infi {ι : Sort u_1} {ι' : Sort u_2} [nonempty ι] [nonempty ι'] {f : ι → nnreal} {g : ι' → nnreal} {a : nnreal} (h : ∀ (i : ι) (j : ι'), a ≤ f i + g j) :
a ≤ (⨅ (i : ι), f i) + ⨅ (j : ι'), g j
theorem nnreal.le_of_forall_pos_le_add {a b : nnreal} (h : ∀ (ε : nnreal), 0 < ε → a ≤ b + ε) :
a ≤ b
theorem nnreal.lt_iff_exists_rat_btwn (a b : nnreal) :
a < b ↔ ∃ (q : ℚ), 0 ≤ q ∧ a < ↑q.to_nnreal ∧ ↑q.to_nnreal < b
theorem nnreal.bot_eq_zero  :
⊥ = 0
theorem nnreal.mul_sup (a b c : nnreal) :
a * (b ⊔ c) = a * b ⊔ a * c
theorem nnreal.sup_mul (a b c : nnreal) :
(a ⊔ b) * c = a * c ⊔ b * c
theorem nnreal.mul_finset_sup {α : Type u_1} (r : nnreal) (s : finset α) (f : α → nnreal) :
r * s.sup f = s.sup (λ (a : α), r * f a)
theorem nnreal.finset_sup_mul {α : Type u_1} (s : finset α) (f : α → nnreal) (r : nnreal) :
s.sup f * r = s.sup (λ (a : α), f a * r)
theorem nnreal.finset_sup_div {α : Type u_1} {f : α → nnreal} {s : finset α} (r : nnreal) :
s.sup f / r = s.sup (λ (a : α), f a / r)
@[simp, norm_cast]
@[simp, norm_cast]
@[simp]
theorem nnreal.zero_le_coe {q : nnreal} :
0 ≤ ↑q
@[simp]
theorem real.to_nnreal_zero  :
@[simp]
theorem real.to_nnreal_one  :
@[simp]
theorem real.to_nnreal_pos {r : ℝ} :
0 < r.to_nnreal ↔ 0 < r
@[simp]
theorem real.to_nnreal_eq_zero {r : ℝ} :
r.to_nnreal = 0 ↔ r ≤ 0
theorem real.to_nnreal_of_nonpos {r : ℝ} :
r ≤ 0 → r.to_nnreal = 0
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theorem real.to_nnreal_le_to_nnreal_iff {r p : ℝ} (hp : 0 ≤ p) :
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theorem real.to_nnreal_lt_to_nnreal_iff {r p : ℝ} (h : 0 < p) :
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theorem real.to_nnreal_add {r p : ℝ} (hr : 0 ≤ r) (hp : 0 ≤ p) :
theorem real.to_nnreal_add_to_nnreal {r p : ℝ} (hr : 0 ≤ r) (hp : 0 ≤ p) :
theorem real.to_nnreal_le_to_nnreal {r p : ℝ} (h : r ≤ p) :
theorem real.le_to_nnreal_iff_coe_le {r : nnreal} {p : ℝ} (hp : 0 ≤ p) :
theorem real.le_to_nnreal_iff_coe_le' {r : nnreal} {p : ℝ} (hr : 0 < r) :
theorem real.to_nnreal_lt_iff_lt_coe {r : ℝ} {p : nnreal} (ha : 0 ≤ r) :
theorem real.lt_to_nnreal_iff_coe_lt {r : nnreal} {p : ℝ} :
@[simp]
@[simp]
theorem real.to_nnreal_bit1 {r : ℝ} (hr : 0 ≤ r) :
theorem nnreal.mul_eq_mul_left {a b c : nnreal} (h : a ≠ 0) :
a * b = a * c ↔ b = c
theorem real.to_nnreal_mul {p q : ℝ} (hp : 0 ≤ p) :
theorem nnreal.pow_antitone_exp {a : nnreal} (m n : ℕ) (mn : m ≤ n) (a1 : a ≤ 1) :
a ^ n ≤ a ^ m
theorem nnreal.exists_pow_lt_of_lt_one {a b : nnreal} (ha : 0 < a) (hb : b < 1) :
∃ (n : ℕ), b ^ n < a
theorem nnreal.exists_mem_Ico_zpow {x y : nnreal} (hx : x ≠ 0) (hy : 1 < y) :
∃ (n : ℤ), x ∈ set.Ico (y ^ n) (y ^ (n + 1))
theorem nnreal.exists_mem_Ioc_zpow {x y : nnreal} (hx : x ≠ 0) (hy : 1 < y) :
∃ (n : ℤ), x ∈ set.Ioc (y ^ n) (y ^ (n + 1))

Lemmas about subtraction #

In this section we provide a few lemmas about subtraction that do not fit well into any other typeclass. For lemmas about subtraction and addition see lemmas about has_ordered_sub in the file algebra.order.sub. See also mul_tsub and tsub_mul.

theorem nnreal.sub_def {r p : nnreal} :
r - p = (↑r - ↑p).to_nnreal
theorem nnreal.coe_sub_def {r p : nnreal} :
theorem nnreal.sub_div (a b c : nnreal) :
(a - b) / c = a / c - b / c
theorem nnreal.sum_div {ι : Type u_1} (s : finset ι) (f : ι → nnreal) (b : nnreal) :
s.sum (λ (i : ι), f i) / b = s.sum (λ (i : ι), f i / b)
@[simp]
theorem nnreal.inv_pos {r : nnreal} :
0 < r⁻¹ ↔ 0 < r
theorem nnreal.div_pos {r p : nnreal} (hr : 0 < r) (hp : 0 < p) :
0 < r / p
theorem nnreal.div_self_le (r : nnreal) :
r / r ≤ 1
@[simp]
theorem nnreal.inv_le {r p : nnreal} (h : r ≠ 0) :
r⁻¹ ≤ p ↔ 1 ≤ r * p
theorem nnreal.inv_le_of_le_mul {r p : nnreal} (h : 1 ≤ r * p) :
@[simp]
theorem nnreal.le_inv_iff_mul_le {r p : nnreal} (h : p ≠ 0) :
r ≤ p⁻¹ ↔ r * p ≤ 1
@[simp]
theorem nnreal.lt_inv_iff_mul_lt {r p : nnreal} (h : p ≠ 0) :
r < p⁻¹ ↔ r * p < 1
theorem nnreal.mul_le_iff_le_inv {a b r : nnreal} (hr : r ≠ 0) :
r * a ≤ b ↔ a ≤ r⁻¹ * b
theorem nnreal.le_div_iff_mul_le {a b r : nnreal} (hr : r ≠ 0) :
a ≤ b / r ↔ a * r ≤ b
theorem nnreal.div_le_iff {a b r : nnreal} (hr : r ≠ 0) :
a / r ≤ b ↔ a ≤ b * r
theorem nnreal.div_le_iff' {a b r : nnreal} (hr : r ≠ 0) :
a / r ≤ b ↔ a ≤ r * b
theorem nnreal.div_le_of_le_mul {a b c : nnreal} (h : a ≤ b * c) :
a / c ≤ b
theorem nnreal.div_le_of_le_mul' {a b c : nnreal} (h : a ≤ b * c) :
a / b ≤ c
theorem nnreal.le_div_iff {a b r : nnreal} (hr : r ≠ 0) :
a ≤ b / r ↔ a * r ≤ b
theorem nnreal.le_div_iff' {a b r : nnreal} (hr : r ≠ 0) :
a ≤ b / r ↔ r * a ≤ b
theorem nnreal.div_lt_iff {a b r : nnreal} (hr : r ≠ 0) :
a / r < b ↔ a < b * r
theorem nnreal.div_lt_iff' {a b r : nnreal} (hr : r ≠ 0) :
a / r < b ↔ a < r * b
theorem nnreal.lt_div_iff {a b r : nnreal} (hr : r ≠ 0) :
a < b / r ↔ a * r < b
theorem nnreal.lt_div_iff' {a b r : nnreal} (hr : r ≠ 0) :
a < b / r ↔ r * a < b
theorem nnreal.mul_lt_of_lt_div {a b r : nnreal} (h : a < b / r) :
a * r < b
theorem nnreal.div_le_div_left_of_le {a b c : nnreal} (b0 : 0 < b) (c0 : 0 < c) (cb : c ≤ b) :
a / b ≤ a / c
theorem nnreal.div_le_div_left {a b c : nnreal} (a0 : 0 < a) (b0 : 0 < b) (c0 : 0 < c) :
a / b ≤ a / c ↔ c ≤ b
theorem nnreal.le_of_forall_lt_one_mul_le {x y : nnreal} (h : ∀ (a : nnreal), a < 1 → a * x ≤ y) :
x ≤ y
theorem nnreal.div_add_div_same (a b c : nnreal) :
a / c + b / c = (a + b) / c
theorem nnreal.half_pos {a : nnreal} (h : 0 < a) :
0 < a / 2
theorem nnreal.add_halves (a : nnreal) :
a / 2 + a / 2 = a
theorem nnreal.half_le_self (a : nnreal) :
a / 2 ≤ a
theorem nnreal.half_lt_self {a : nnreal} (h : a ≠ 0) :
a / 2 < a
theorem nnreal.div_lt_one_of_lt {a b : nnreal} (h : a < b) :
a / b < 1
theorem nnreal.div_add_div (a : nnreal) {b : nnreal} (c : nnreal) {d : nnreal} (hb : b ≠ 0) (hd : d ≠ 0) :
a / b + c / d = (a * d + b * c) / (b * d)
theorem nnreal.add_div' (a b c : nnreal) (hc : c ≠ 0) :
b + a / c = (b * c + a) / c
theorem nnreal.div_add' (a b c : nnreal) (hc : c ≠ 0) :
a / c + b = (a + b * c) / c
theorem real.to_nnreal_div {x y : ℝ} (hx : 0 ≤ x) :
theorem real.to_nnreal_div' {x y : ℝ} (hy : 0 ≤ y) :
theorem nnreal.inv_lt_one_iff {x : nnreal} (hx : x ≠ 0) :
x⁻¹ < 1 ↔ 1 < x
theorem nnreal.inv_lt_one {x : nnreal} (hx : 1 < x) :
x⁻¹ < 1
theorem nnreal.zpow_pos {x : nnreal} (hx : x ≠ 0) (n : ℤ) :
0 < x ^ n
theorem nnreal.inv_lt_inv_iff {x y : nnreal} (hx : x ≠ 0) (hy : y ≠ 0) :
y⁻¹ < x⁻¹ ↔ x < y
theorem nnreal.inv_lt_inv {x y : nnreal} (hx : x ≠ 0) (h : x < y) :
@[simp]
theorem nnreal.abs_eq (x : nnreal) :
theorem nnreal.le_to_nnreal_of_coe_le {x : nnreal} {y : ℝ} (h : ↑x ≤ y) :
theorem nnreal.supr_of_not_bdd_above {ι : Sort u_1} {f : ι → nnreal} (hf : ¬bdd_above (set.range f)) :
(⨆ (i : ι), f i) = 0
theorem nnreal.infi_empty {ι : Sort u_1} [is_empty ι] (f : ι → nnreal) :
(⨅ (i : ι), f i) = 0
@[simp]
theorem nnreal.infi_const_zero {α : Sort u_1} :
(⨅ (i : α), 0) = 0
theorem nnreal.infi_mul {ι : Sort u_1} (f : ι → nnreal) (a : nnreal) :
infi f * a = ⨅ (i : ι), f i * a
theorem nnreal.mul_infi {ι : Sort u_1} (f : ι → nnreal) (a : nnreal) :
a * infi f = ⨅ (i : ι), a * f i
theorem nnreal.mul_supr {ι : Sort u_1} (f : ι → nnreal) (a : nnreal) :
(a * ⨆ (i : ι), f i) = ⨆ (i : ι), a * f i
theorem nnreal.supr_mul {ι : Sort u_1} (f : ι → nnreal) (a : nnreal) :
(⨆ (i : ι), f i) * a = ⨆ (i : ι), f i * a
theorem nnreal.supr_div {ι : Sort u_1} (f : ι → nnreal) (a : nnreal) :
(⨆ (i : ι), f i) / a = ⨆ (i : ι), f i / a
theorem nnreal.le_mul_infi {ι : Sort u_1} [nonempty ι] {a g : nnreal} {h : ι → nnreal} (H : ∀ (j : ι), a ≤ g * h j) :
a ≤ g * infi h
theorem nnreal.mul_supr_le {ι : Sort u_1} [nonempty ι] {a g : nnreal} {h : ι → nnreal} (H : ∀ (j : ι), g * h j ≤ a) :
g * supr h ≤ a
theorem nnreal.le_infi_mul {ι : Sort u_1} [nonempty ι] {a : nnreal} {g : ι → nnreal} {h : nnreal} (H : ∀ (i : ι), a ≤ g i * h) :
a ≤ infi g * h
theorem nnreal.supr_mul_le {ι : Sort u_1} [nonempty ι] {a : nnreal} {g : ι → nnreal} {h : nnreal} (H : ∀ (i : ι), g i * h ≤ a) :
supr g * h ≤ a
theorem nnreal.le_infi_mul_infi {ι : Sort u_1} [nonempty ι] {a : nnreal} {g h : ι → nnreal} (H : ∀ (i j : ι), a ≤ g i * h j) :
a ≤ infi g * infi h
theorem nnreal.supr_mul_supr_le {ι : Sort u_1} [nonempty ι] {a : nnreal} {g h : ι → nnreal} (H : ∀ (i j : ι), g i * h j ≤ a) :
supr g * supr h ≤ a
noncomputable def real.nnabs  :

The absolute value on ℝ as a map to ℝ≥0.

Equations
@[simp, norm_cast]
theorem real.coe_nnabs (x : ℝ) :
@[simp]
theorem real.nnabs_of_nonneg {x : ℝ} (h : 0 ≤ x) :