Absolute values in ordered groups

The absolute value of an element in a group which is also a lattice is its supremum with its negation. This generalizes the usual absolute value on real numbers (|x| = max x (-x)).

Notations

• |a|: The absolute value of an element a of an additive lattice ordered group
• |a|ₘ: The absolute value of an element a of a multiplicative lattice ordered group

def abs {α : Type u_1} [Lattice α] [AddGroup α] (a : α) : α

abs a is the absolute value of a

Equations

• |a| = a ⊔ -a

def mabs {α : Type u_1} [Lattice α] [Group α] (a : α) : α

mabs a is the absolute value of a.

Equations

• mabs a = a ⊔ a⁻¹

def «term|___|ₘ» : Lean.ParserDescr

mabs a is the absolute value of a.

Equations

• One or more equations did not get rendered due to their size.

def «term|___|» : Lean.ParserDescr

abs a is the absolute value of a

Equations

• One or more equations did not get rendered due to their size.

def mabs.unexpander : Lean.PrettyPrinter.Unexpander

Unexpander for the notation |a|ₘ for mabs a. Tries to add discretionary parentheses in unparseable cases.

Equations

• One or more equations did not get rendered due to their size.

def abs.unexpander : Lean.PrettyPrinter.Unexpander

Unexpander for the notation |a| for abs a. Tries to add discretionary parentheses in unparseable cases.

Equations

• One or more equations did not get rendered due to their size.

theorem abs_le' {α : Type u_1} [Lattice α] [AddGroup α] {a : α} {b : α} : |a| ≤ b ↔ a ≤ b ∧ -a ≤ b

theorem mabs_le' {α : Type u_1} [Lattice α] [Group α] {a : α} {b : α} : mabs a ≤ b ↔ a ≤ b ∧ a⁻¹ ≤ b

theorem le_abs_self {α : Type u_1} [Lattice α] [AddGroup α] (a : α) : a ≤ |a|

theorem le_mabs_self {α : Type u_1} [Lattice α] [Group α] (a : α) : a ≤ mabs a

theorem neg_le_abs {α : Type u_1} [Lattice α] [AddGroup α] (a : α) : -a ≤ |a|

theorem inv_le_mabs {α : Type u_1} [Lattice α] [Group α] (a : α) : a⁻¹ ≤ mabs a

theorem abs_le_abs {α : Type u_1} [Lattice α] [AddGroup α] {a : α} {b : α} (h₀ : a ≤ b) (h₁ : -a ≤ b) : |a| ≤ |b|

theorem mabs_le_mabs {α : Type u_1} [Lattice α] [Group α] {a : α} {b : α} (h₀ : a ≤ b) (h₁ : a⁻¹ ≤ b) : mabs a ≤ mabs b

@[simp]

theorem abs_neg {α : Type u_1} [Lattice α] [AddGroup α] (a : α) : |(-a)| = |a|

@[simp]

theorem mabs_inv {α : Type u_1} [Lattice α] [Group α] (a : α) : mabs a⁻¹ = mabs a

theorem abs_sub_comm {α : Type u_1} [Lattice α] [AddGroup α] (a : α) (b : α) : |a - b| = |b - a|

theorem mabs_div_comm {α : Type u_1} [Lattice α] [Group α] (a : α) (b : α) : mabs (a / b) = mabs (b / a)

theorem abs_of_nonneg {α : Type u_1} [Lattice α] [AddGroup α] {a : α} [AddLeftMono α] (h : 0 ≤ a) : |a| = a

theorem mabs_of_one_le {α : Type u_1} [Lattice α] [Group α] {a : α} [MulLeftMono α] (h : 1 ≤ a) : mabs a = a

theorem abs_of_pos {α : Type u_1} [Lattice α] [AddGroup α] {a : α} [AddLeftMono α] (h : 0 < a) : |a| = a

theorem mabs_of_one_lt {α : Type u_1} [Lattice α] [Group α] {a : α} [MulLeftMono α] (h : 1 < a) : mabs a = a

theorem abs_of_nonpos {α : Type u_1} [Lattice α] [AddGroup α] {a : α} [AddLeftMono α] (h : a ≤ 0) : |a| = -a

theorem mabs_of_le_one {α : Type u_1} [Lattice α] [Group α] {a : α} [MulLeftMono α] (h : a ≤ 1) : mabs a = a⁻¹

theorem abs_of_neg {α : Type u_1} [Lattice α] [AddGroup α] {a : α} [AddLeftMono α] (h : a < 0) : |a| = -a

theorem mabs_of_lt_one {α : Type u_1} [Lattice α] [Group α] {a : α} [MulLeftMono α] (h : a < 1) : mabs a = a⁻¹

theorem abs_le_abs_of_nonneg {α : Type u_1} [Lattice α] [AddGroup α] {a : α} {b : α} [AddLeftMono α] (ha : 0 ≤ a) (hab : a ≤ b) : |a| ≤ |b|

theorem mabs_le_mabs_of_one_le {α : Type u_1} [Lattice α] [Group α] {a : α} {b : α} [MulLeftMono α] (ha : 1 ≤ a) (hab : a ≤ b) : mabs a ≤ mabs b

@[simp]

theorem abs_zero {α : Type u_1} [Lattice α] [AddGroup α] [AddLeftMono α] : |0| = 0

@[simp]

theorem mabs_one {α : Type u_1} [Lattice α] [Group α] [MulLeftMono α] : mabs 1 = 1

@[simp]

theorem abs_nonneg {α : Type u_1} [Lattice α] [AddGroup α] [AddLeftMono α] [AddRightMono α] (a : α) : 0 ≤ |a|

@[simp]

theorem one_le_mabs {α : Type u_1} [Lattice α] [Group α] [MulLeftMono α] [MulRightMono α] (a : α) : 1 ≤ mabs a

@[simp]

theorem abs_abs {α : Type u_1} [Lattice α] [AddGroup α] [AddLeftMono α] [AddRightMono α] (a : α) : |(|a|)| = |a|

@[simp]

theorem mabs_mabs {α : Type u_1} [Lattice α] [Group α] [MulLeftMono α] [MulRightMono α] (a : α) : mabs (mabs a) = mabs a

theorem abs_add_le {α : Type u_1} [Lattice α] [AddCommGroup α] [AddLeftMono α] (a : α) (b : α) : |a + b| ≤ |a| + |b|

The absolute value satisfies the triangle inequality.

theorem mabs_mul_le {α : Type u_1} [Lattice α] [CommGroup α] [MulLeftMono α] (a : α) (b : α) : mabs (a * b) ≤ mabs a * mabs b

The absolute value satisfies the triangle inequality.

theorem abs_abs_sub_abs_le {α : Type u_1} [Lattice α] [AddCommGroup α] [AddLeftMono α] (a : α) (b : α) : ||a| - |b|| ≤ |a - b|

theorem mabs_mabs_div_mabs_le {α : Type u_1} [Lattice α] [CommGroup α] [MulLeftMono α] (a : α) (b : α) : mabs (mabs a / mabs b) ≤ mabs (a / b)

theorem sup_sub_inf_eq_abs_sub {α : Type u_1} [Lattice α] [AddCommGroup α] [AddLeftMono α] (a : α) (b : α) : a ⊔ b - a ⊓ b = |b - a|

theorem sup_div_inf_eq_mabs_div {α : Type u_1} [Lattice α] [CommGroup α] [MulLeftMono α] (a : α) (b : α) : (a ⊔ b) / (a ⊓ b) = mabs (b / a)

theorem two_nsmul_sup_eq_add_add_abs_sub {α : Type u_1} [Lattice α] [AddCommGroup α] [AddLeftMono α] (a : α) (b : α) : 2 • (a ⊔ b) = a + b + |b - a|

theorem sup_sq_eq_mul_mul_mabs_div {α : Type u_1} [Lattice α] [CommGroup α] [MulLeftMono α] (a : α) (b : α) : (a ⊔ b) ^ 2 = a * b * mabs (b / a)

theorem two_nsmul_inf_eq_add_sub_abs_sub {α : Type u_1} [Lattice α] [AddCommGroup α] [AddLeftMono α] (a : α) (b : α) : 2 • (a ⊓ b) = a + b - |b - a|

theorem inf_sq_eq_mul_div_mabs_div {α : Type u_1} [Lattice α] [CommGroup α] [MulLeftMono α] (a : α) (b : α) : (a ⊓ b) ^ 2 = a * b / mabs (b / a)

theorem abs_sub_sup_add_abs_sub_inf {α : Type u_1} [Lattice α] [AddCommGroup α] [AddLeftMono α] (a : α) (b : α) (c : α) : |a ⊔ c - b ⊔ c| + |a ⊓ c - b ⊓ c| = |a - b|

theorem mabs_div_sup_mul_mabs_div_inf {α : Type u_1} [Lattice α] [CommGroup α] [MulLeftMono α] (a : α) (b : α) (c : α) : mabs ((a ⊔ c) / (b ⊔ c)) * mabs ((a ⊓ c) / (b ⊓ c)) = mabs (a / b)

theorem abs_sup_sub_sup_le_abs {α : Type u_1} [Lattice α] [AddCommGroup α] [AddLeftMono α] (a : α) (b : α) (c : α) : |a ⊔ c - b ⊔ c| ≤ |a - b|

theorem mabs_sup_div_sup_le_mabs {α : Type u_1} [Lattice α] [CommGroup α] [MulLeftMono α] (a : α) (b : α) (c : α) : mabs ((a ⊔ c) / (b ⊔ c)) ≤ mabs (a / b)

theorem abs_inf_sub_inf_le_abs {α : Type u_1} [Lattice α] [AddCommGroup α] [AddLeftMono α] (a : α) (b : α) (c : α) : |a ⊓ c - b ⊓ c| ≤ |a - b|

theorem mabs_inf_div_inf_le_mabs {α : Type u_1} [Lattice α] [CommGroup α] [MulLeftMono α] (a : α) (b : α) (c : α) : mabs ((a ⊓ c) / (b ⊓ c)) ≤ mabs (a / b)

theorem Birkhoff_inequalities {α : Type u_1} [Lattice α] [AddCommGroup α] [AddLeftMono α] (a : α) (b : α) (c : α) : |a ⊔ c - b ⊔ c| ⊔ |a ⊓ c - b ⊓ c| ≤ |a - b|

theorem m_Birkhoff_inequalities {α : Type u_1} [Lattice α] [CommGroup α] [MulLeftMono α] (a : α) (b : α) (c : α) : mabs ((a ⊔ c) / (b ⊔ c)) ⊔ mabs ((a ⊓ c) / (b ⊓ c)) ≤ mabs (a / b)

theorem abs_choice {α : Type u_1} [AddGroup α] [LinearOrder α] (x : α) : |x| = x ∨ |x| = -x

theorem mabs_choice {α : Type u_1} [Group α] [LinearOrder α] (x : α) : mabs x = x ∨ mabs x = x⁻¹

theorem le_abs {α : Type u_1} [AddGroup α] [LinearOrder α] {a : α} {b : α} : a ≤ |b| ↔ a ≤ b ∨ a ≤ -b

theorem le_mabs {α : Type u_1} [Group α] [LinearOrder α] {a : α} {b : α} : a ≤ mabs b ↔ a ≤ b ∨ a ≤ b⁻¹

theorem abs_eq_max_neg {α : Type u_1} [AddGroup α] [LinearOrder α] {a : α} : |a| = max a (-a)

theorem mabs_eq_max_inv {α : Type u_1} [Group α] [LinearOrder α] {a : α} : mabs a = max a a⁻¹

theorem lt_abs {α : Type u_1} [AddGroup α] [LinearOrder α] {a : α} {b : α} : a < |b| ↔ a < b ∨ a < -b

theorem lt_mabs {α : Type u_1} [Group α] [LinearOrder α] {a : α} {b : α} : a < mabs b ↔ a < b ∨ a < b⁻¹

theorem abs_by_cases {α : Type u_1} [AddGroup α] [LinearOrder α] {a : α} (P : α → Prop) (h1 : P a) (h2 : P (-a)) : P |a|

theorem mabs_by_cases {α : Type u_1} [Group α] [LinearOrder α] {a : α} (P : α → Prop) (h1 : P a) (h2 : P a⁻¹) : P (mabs a)

theorem eq_or_eq_neg_of_abs_eq {α : Type u_1} [AddGroup α] [LinearOrder α] {a : α} {b : α} (h : |a| = b) : a = b ∨ a = -b

theorem eq_or_eq_inv_of_mabs_eq {α : Type u_1} [Group α] [LinearOrder α] {a : α} {b : α} (h : mabs a = b) : a = b ∨ a = b⁻¹

theorem abs_eq_abs {α : Type u_1} [AddGroup α] [LinearOrder α] {a : α} {b : α} : |a| = |b| ↔ a = b ∨ a = -b

theorem mabs_eq_mabs {α : Type u_1} [Group α] [LinearOrder α] {a : α} {b : α} : mabs a = mabs b ↔ a = b ∨ a = b⁻¹

theorem even_abs {α : Type u_1} [AddGroup α] [LinearOrder α] {a : α} : Even |a| ↔ Even a

theorem isSquare_mabs {α : Type u_1} [Group α] [LinearOrder α] {a : α} : IsSquare (mabs a) ↔ IsSquare a

theorem lt_of_abs_lt {α : Type u_1} [AddGroup α] [LinearOrder α] {a : α} {b : α} : |a| < b → a < b

theorem lt_of_mabs_lt {α : Type u_1} [Group α] [LinearOrder α] {a : α} {b : α} : mabs a < b → a < b

@[simp]

theorem abs_pos {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] {a : α} : 0 < |a| ↔ a ≠ 0

@[simp]

theorem one_lt_mabs {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] {a : α} : 1 < mabs a ↔ a ≠ 1

theorem abs_pos_of_pos {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] {a : α} (h : 0 < a) : 0 < |a|

theorem one_lt_mabs_pos_of_one_lt {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] {a : α} (h : 1 < a) : 1 < mabs a

theorem abs_pos_of_neg {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] {a : α} (h : a < 0) : 0 < |a|

theorem one_lt_mabs_of_lt_one {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] {a : α} (h : a < 1) : 1 < mabs a

theorem neg_abs_le {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] (a : α) : -|a| ≤ a

theorem inv_mabs_le {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] (a : α) : (mabs a)⁻¹ ≤ a

theorem add_abs_nonneg {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] (a : α) : 0 ≤ a + |a|

theorem one_le_mul_mabs {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] (a : α) : 1 ≤ a * mabs a

theorem neg_abs_le_neg {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] (a : α) : -|a| ≤ -a

theorem inv_mabs_le_inv {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] (a : α) : (mabs a)⁻¹ ≤ a⁻¹

theorem abs_ne_zero {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] {a : α} [AddRightMono α] : |a| ≠ 0 ↔ a ≠ 0

theorem mabs_ne_one {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] {a : α} [MulRightMono α] : mabs a ≠ 1 ↔ a ≠ 1

@[simp]

theorem abs_eq_zero {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] {a : α} [AddRightMono α] : |a| = 0 ↔ a = 0

@[simp]

theorem mabs_eq_one {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] {a : α} [MulRightMono α] : mabs a = 1 ↔ a = 1

@[simp]

theorem abs_nonpos_iff {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] {a : α} [AddRightMono α] : |a| ≤ 0 ↔ a = 0

@[simp]

theorem mabs_le_one {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] {a : α} [MulRightMono α] : mabs a ≤ 1 ↔ a = 1

theorem abs_le_abs_of_nonpos {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] {a : α} {b : α} [AddRightMono α] (ha : a ≤ 0) (hab : b ≤ a) : |a| ≤ |b|

theorem mabs_le_mabs_of_le_one {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] {a : α} {b : α} [MulRightMono α] (ha : a ≤ 1) (hab : b ≤ a) : mabs a ≤ mabs b

theorem abs_lt {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] {a : α} {b : α} [AddRightMono α] : |a| < b ↔ -b < a ∧ a < b

theorem mabs_lt {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] {a : α} {b : α} [MulRightMono α] : mabs a < b ↔ b⁻¹ < a ∧ a < b

theorem neg_lt_of_abs_lt {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] {a : α} {b : α} [AddRightMono α] (h : |a| < b) : -b < a

theorem inv_lt_of_mabs_lt {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] {a : α} {b : α} [MulRightMono α] (h : mabs a < b) : b⁻¹ < a

theorem max_sub_min_eq_abs' {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] [AddRightMono α] (a : α) (b : α) : max a b - min a b = |a - b|

theorem max_div_min_eq_mabs' {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] [MulRightMono α] (a : α) (b : α) : max a b / min a b = mabs (a / b)

theorem max_sub_min_eq_abs {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] [AddRightMono α] (a : α) (b : α) : max a b - min a b = |b - a|

theorem max_div_min_eq_mabs {α : Type u_1} [Group α] [LinearOrder α] [MulLeftMono α] [MulRightMono α] (a : α) (b : α) : max a b / min a b = mabs (b / a)

def LatticeOrderedAddCommGroup.IsSolid {α : Type u_1} [Lattice α] [AddCommGroup α] (s : Set α) : Prop

A set s in a lattice ordered group is solid if for all x ∈ s and all y ∈ α such that |y| ≤ |x|, then y ∈ s.

Equations

• LatticeOrderedAddCommGroup.IsSolid s = ∀ ⦃x : α⦄, x ∈ s → ∀ ⦃y : α⦄, |y| ≤ |x| → y ∈ s

def LatticeOrderedAddCommGroup.solidClosure {α : Type u_1} [Lattice α] [AddCommGroup α] (s : Set α) : Set α

The solid closure of a subset s is the smallest superset of s that is solid.

Equations

• LatticeOrderedAddCommGroup.solidClosure s = {y : α | ∃ (x : α), x ∈ s ∧ |y| ≤ |x|}

theorem LatticeOrderedAddCommGroup.isSolid_solidClosure {α : Type u_1} [Lattice α] [AddCommGroup α] (s : Set α) : LatticeOrderedAddCommGroup.IsSolid (LatticeOrderedAddCommGroup.solidClosure s)

theorem LatticeOrderedAddCommGroup.solidClosure_min {α : Type u_1} [Lattice α] [AddCommGroup α] {s : Set α} {t : Set α} (hst : s ⊆ t) (ht : LatticeOrderedAddCommGroup.IsSolid t) : LatticeOrderedAddCommGroup.solidClosure s ⊆ t

@[simp]

theorem Pi.abs_apply {ι : Type u_2} {α : ι → Type u_3} [(i : ι) → AddGroup (α i)] [(i : ι) → Lattice (α i)] (f : (i : ι) → α i) (i : ι) : |f| i = |f i|

theorem Pi.abs_def {ι : Type u_2} {α : ι → Type u_3} [(i : ι) → AddGroup (α i)] [(i : ι) → Lattice (α i)] (f : (i : ι) → α i) : |f| = fun (i : ι) => |f i|

@[deprecated neg_le_abs]

theorem neg_le_abs_self {α : Type u_1} [Lattice α] [AddGroup α] (a : α) : -a ≤ |a|

Alias of neg_le_abs.

@[deprecated neg_abs_le]

theorem neg_abs_le_self {α : Type u_1} [AddGroup α] [LinearOrder α] [AddLeftMono α] (a : α) : -|a| ≤ a

Alias of neg_abs_le.