mathlib documentation

@[class]

structure normalization_monoid (α : Type u_2) [cancel_comm_monoid_with_zero α] :

Type u_2

norm_unit : α → units α
norm_unit_zero : norm_unit 0 = 1
norm_unit_mul : ∀ {a b : α}, a ≠ 0 → b ≠ 0 → norm_unit (a * b) = (norm_unit a) * norm_unit b
norm_unit_coe_units : ∀ (u : units α), norm_unit ↑u = u⁻¹

Normalization monoid: multiplying with norm_unit gives a normal form for associated elements.

Instances

@[simp]

theorem norm_unit_one {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] :

norm_unit 1 = 1

def normalize {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] :

monoid_with_zero_hom α α

Chooses an element of each associate class, by multiplying by norm_unit

Equations

normalize = {to_fun := λ (x : α), x * ↑(norm_unit x), map_zero' := _, map_one' := _, map_mul' := _}

theorem associated_normalize {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (x : α) :

associated x (⇑normalize x)

theorem normalize_associated {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (x : α) :

associated (⇑normalize x) x

theorem associates.mk_normalize {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (x : α) :

associates.mk (⇑normalize x) = associates.mk x

@[simp]

theorem normalize_apply {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (x : α) :

⇑normalize x = x * ↑(norm_unit x)

@[simp]

theorem normalize_zero {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] :

⇑normalize 0 = 0

@[simp]

theorem normalize_one {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] :

⇑normalize 1 = 1

theorem normalize_coe_units {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (u : units α) :

⇑normalize ↑u = 1

theorem normalize_eq_zero {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] {x : α} :

⇑normalize x = 0 ↔ x = 0

theorem normalize_eq_one {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] {x : α} :

⇑normalize x = 1 ↔ is_unit x

@[simp]

theorem norm_unit_mul_norm_unit {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (a : α) :

norm_unit (a * ↑(norm_unit a)) = 1

theorem normalize_idem {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (x : α) :

⇑normalize (⇑normalize x) = ⇑normalize x

theorem normalize_eq_normalize {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] {a b : α} (hab : a ∣ b) (hba : b ∣ a) :

⇑normalize a = ⇑normalize b

theorem normalize_eq_normalize_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] {x y : α} :

⇑normalize x = ⇑normalize y ↔ x ∣ y ∧ y ∣ x

theorem dvd_antisymm_of_normalize_eq {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] {a b : α} (ha : ⇑normalize a = a) (hb : ⇑normalize b = b) (hab : a ∣ b) (hba : b ∣ a) :

a = b

theorem dvd_normalize_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] {a b : α} :

a ∣ ⇑normalize b ↔ a ∣ b

theorem normalize_dvd_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] {a b : α} :

⇑normalize a ∣ b ↔ a ∣ b

@[protected]

def associates.out {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] :

associates α → α

Maps an element of associates back to the normalized element of its associate class

Equations

associates.out = quotient.lift ⇑normalize associates.out._proof_1

@[simp]

theorem associates.out_mk {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (a : α) :

(associates.mk a).out = ⇑normalize a

@[simp]

theorem associates.out_one {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] :

1.out = 1

theorem associates.out_mul {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (a b : associates α) :

(a * b).out = (a.out) * b.out

theorem associates.dvd_out_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (a : α) (b : associates α) :

a ∣ b.out ↔ associates.mk a ≤ b

theorem associates.out_dvd_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (a : α) (b : associates α) :

b.out ∣ a ↔ b ≤ associates.mk a

@[simp]

theorem associates.out_top {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] :

⊤.out = 0

@[simp]

theorem associates.normalize_out {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (a : associates α) :

⇑normalize a.out = a.out

@[simp]

theorem associates.mk_out {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] (a : associates α) :

associates.mk a.out = a

function.injective associates.out

theorem associates.out_injective {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] :

@[class]

structure gcd_monoid (α : Type u_2) [cancel_comm_monoid_with_zero α] :

Type u_2

gcd : α → α → α
lcm : α → α → α
gcd_dvd_left : ∀ (a b : α), gcd a b ∣ a
gcd_dvd_right : ∀ (a b : α), gcd a b ∣ b
dvd_gcd : ∀ {a b c : α}, a ∣ c → a ∣ b → a ∣ gcd c b
gcd_mul_lcm : ∀ (a b : α), associated ((gcd a b) * lcm a b) (a * b)
lcm_zero_left : ∀ (a : α), lcm 0 a = 0
lcm_zero_right : ∀ (a : α), lcm a 0 = 0

GCD monoid: a cancel_comm_monoid_with_zero with gcd (greatest common divisor) and lcm (least common multiple) operations, determined up to a unit. The type class focuses on gcd and we derive the corresponding lcm facts from gcd.

Instances

normalized_gcd_monoid.to_gcd_monoid

@[class]

structure normalized_gcd_monoid (α : Type u_2) [cancel_comm_monoid_with_zero α] :

Type u_2

to_normalization_monoid : normalization_monoid α
to_gcd_monoid : gcd_monoid α
normalize_gcd : ∀ (a b : α), ⇑normalize (gcd a b) = gcd a b
normalize_lcm : ∀ (a b : α), ⇑normalize (lcm a b) = lcm a b

Normalized GCD monoid: a cancel_comm_monoid_with_zero with normalization and gcd (greatest common divisor) and lcm (least common multiple) operations. In this setting gcd and lcm form a bounded lattice on the associated elements where gcd is the infimum, lcm is the supremum, 1 is bottom, and 0 is top. The type class focuses on gcd and we derive the corresponding lcm facts from gcd.

Instances

@[simp]

theorem normalize_gcd {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b : α) :

⇑normalize (gcd a b) = gcd a b

theorem gcd_mul_lcm {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a b : α) :

associated ((gcd a b) * lcm a b) (a * b)

theorem dvd_gcd_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a b c : α) :

a ∣ gcd b c ↔ a ∣ b ∧ a ∣ c

theorem gcd_comm {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b : α) :

gcd a b = gcd b a

theorem gcd_comm' {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a b : α) :

associated (gcd a b) (gcd b a)

theorem gcd_assoc {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (m n k : α) :

gcd (gcd m n) k = gcd m (gcd n k)

theorem gcd_assoc' {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (m n k : α) :

associated (gcd (gcd m n) k) (gcd m (gcd n k))

@[protected, instance]

def gcd_monoid.gcd.is_commutative {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] :

is_commutative α gcd

@[protected, instance]

def gcd_monoid.gcd.is_associative {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] :

is_associative α gcd

theorem gcd_eq_normalize {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] {a b c : α} (habc : gcd a b ∣ c) (hcab : c ∣ gcd a b) :

gcd a b = ⇑normalize c

@[simp]

theorem gcd_zero_left {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a : α) :

gcd 0 a = ⇑normalize a

theorem gcd_zero_left' {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a : α) :

associated (gcd 0 a) a

@[simp]

theorem gcd_zero_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a : α) :

gcd a 0 = ⇑normalize a

theorem gcd_zero_right' {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a : α) :

associated (gcd a 0) a

@[simp]

theorem gcd_eq_zero_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a b : α) :

gcd a b = 0 ↔ a = 0 ∧ b = 0

@[simp]

theorem gcd_one_left {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a : α) :

gcd 1 a = 1

@[simp]

theorem gcd_one_left' {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a : α) :

associated (gcd 1 a) 1

@[simp]

theorem gcd_one_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a : α) :

gcd a 1 = 1

@[simp]

theorem gcd_one_right' {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a : α) :

associated (gcd a 1) 1

theorem gcd_dvd_gcd {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {a b c d : α} (hab : a ∣ b) (hcd : c ∣ d) :

gcd a c ∣ gcd b d

@[simp]

theorem gcd_same {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a : α) :

gcd a a = ⇑normalize a

@[simp]

theorem gcd_mul_left {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b c : α) :

gcd (a * b) (a * c) = (⇑normalize a) * gcd b c

theorem gcd_mul_left' {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a b c : α) :

associated (gcd (a * b) (a * c)) (a * gcd b c)

@[simp]

theorem gcd_mul_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b c : α) :

gcd (b * a) (c * a) = (gcd b c) * ⇑normalize a

@[simp]

theorem gcd_mul_right' {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a b c : α) :

associated (gcd (b * a) (c * a)) ((gcd b c) * a)

theorem gcd_eq_left_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b : α) (h : ⇑normalize a = a) :

gcd a b = a ↔ a ∣ b

theorem gcd_eq_right_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b : α) (h : ⇑normalize b = b) :

gcd a b = b ↔ b ∣ a

theorem gcd_dvd_gcd_mul_left {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (m n k : α) :

gcd m n ∣ gcd (k * m) n

theorem gcd_dvd_gcd_mul_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (m n k : α) :

gcd m n ∣ gcd (m * k) n

theorem gcd_dvd_gcd_mul_left_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (m n k : α) :

gcd m n ∣ gcd m (k * n)

theorem gcd_dvd_gcd_mul_right_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (m n k : α) :

gcd m n ∣ gcd m (n * k)

theorem associated.gcd_eq_left {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] {m n : α} (h : associated m n) (k : α) :

gcd m k = gcd n k

theorem associated.gcd_eq_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] {m n : α} (h : associated m n) (k : α) :

gcd k m = gcd k n

theorem dvd_gcd_mul_of_dvd_mul {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {m n k : α} (H : k ∣ m * n) :

k ∣ (gcd k m) * n

theorem dvd_mul_gcd_of_dvd_mul {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {m n k : α} (H : k ∣ m * n) :

k ∣ m * gcd k n

theorem exists_dvd_and_dvd_of_dvd_mul {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {m n k : α} (H : k ∣ m * n) :

∃ (d₁ : α) (hd₁ : d₁ ∣ m) (d₂ : α) (hd₂ : d₂ ∣ n), k = d₁ * d₂

Represent a divisor of m * n as a product of a divisor of m and a divisor of n.

Note: In general, this representation is highly non-unique.

theorem gcd_mul_dvd_mul_gcd {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (k m n : α) :

gcd k (m * n) ∣ (gcd k m) * gcd k n

theorem gcd_pow_right_dvd_pow_gcd {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {a b : α} {k : ℕ} :

gcd a (b ^ k) ∣ gcd a b ^ k

theorem gcd_pow_left_dvd_pow_gcd {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {a b : α} {k : ℕ} :

gcd (a ^ k) b ∣ gcd a b ^ k

theorem pow_dvd_of_mul_eq_pow {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {a b c d₁ d₂ : α} (ha : a ≠ 0) (hab : is_unit (gcd a b)) {k : ℕ} (h : a * b = c ^ k) (hc : c = d₁ * d₂) (hd₁ : d₁ ∣ a) :

d₁ ^ k ≠ 0 ∧ d₁ ^ k ∣ a

theorem exists_associated_pow_of_mul_eq_pow {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {a b c : α} (hab : is_unit (gcd a b)) {k : ℕ} (h : a * b = c ^ k) :

∃ (d : α), associated (d ^ k) a

theorem exists_eq_pow_of_mul_eq_pow {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] [unique (units α)] {a b c : α} (hab : is_unit (gcd a b)) {k : ℕ} (h : a * b = c ^ k) :

∃ (d : α), a = d ^ k

theorem lcm_dvd_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {a b c : α} :

lcm a b ∣ c ↔ a ∣ c ∧ b ∣ c

theorem dvd_lcm_left {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a b : α) :

a ∣ lcm a b

theorem dvd_lcm_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a b : α) :

b ∣ lcm a b

theorem lcm_dvd {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {a b c : α} (hab : a ∣ b) (hcb : c ∣ b) :

lcm a c ∣ b

@[simp]

theorem lcm_eq_zero_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a b : α) :

lcm a b = 0 ↔ a = 0 ∨ b = 0

@[simp]

theorem normalize_lcm {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b : α) :

⇑normalize (lcm a b) = lcm a b

theorem lcm_comm {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b : α) :

lcm a b = lcm b a

theorem lcm_comm' {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (a b : α) :

associated (lcm a b) (lcm b a)

theorem lcm_assoc {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (m n k : α) :

lcm (lcm m n) k = lcm m (lcm n k)

theorem lcm_assoc' {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (m n k : α) :

associated (lcm (lcm m n) k) (lcm m (lcm n k))

@[protected, instance]

def gcd_monoid.lcm.is_commutative {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] :

is_commutative α lcm

@[protected, instance]

def gcd_monoid.lcm.is_associative {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] :

is_associative α lcm

theorem lcm_eq_normalize {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] {a b c : α} (habc : lcm a b ∣ c) (hcab : c ∣ lcm a b) :

lcm a b = ⇑normalize c

theorem lcm_dvd_lcm {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {a b c d : α} (hab : a ∣ b) (hcd : c ∣ d) :

lcm a c ∣ lcm b d

@[simp]

theorem lcm_units_coe_left {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (u : units α) (a : α) :

lcm ↑u a = ⇑normalize a

@[simp]

theorem lcm_units_coe_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a : α) (u : units α) :

lcm a ↑u = ⇑normalize a

@[simp]

theorem lcm_one_left {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a : α) :

lcm 1 a = ⇑normalize a

@[simp]

theorem lcm_one_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a : α) :

lcm a 1 = ⇑normalize a

@[simp]

theorem lcm_same {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a : α) :

lcm a a = ⇑normalize a

@[simp]

theorem lcm_eq_one_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b : α) :

lcm a b = 1 ↔ a ∣ 1 ∧ b ∣ 1

@[simp]

theorem lcm_mul_left {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b c : α) :

lcm (a * b) (a * c) = (⇑normalize a) * lcm b c

@[simp]

theorem lcm_mul_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b c : α) :

lcm (b * a) (c * a) = (lcm b c) * ⇑normalize a

theorem lcm_eq_left_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b : α) (h : ⇑normalize a = a) :

lcm a b = a ↔ b ∣ a

theorem lcm_eq_right_iff {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] (a b : α) (h : ⇑normalize b = b) :

lcm a b = b ↔ a ∣ b

theorem lcm_dvd_lcm_mul_left {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (m n k : α) :

lcm m n ∣ lcm (k * m) n

theorem lcm_dvd_lcm_mul_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (m n k : α) :

lcm m n ∣ lcm (m * k) n

theorem lcm_dvd_lcm_mul_left_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (m n k : α) :

lcm m n ∣ lcm m (k * n)

theorem lcm_dvd_lcm_mul_right_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] (m n k : α) :

lcm m n ∣ lcm m (n * k)

theorem lcm_eq_of_associated_left {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] {m n : α} (h : associated m n) (k : α) :

lcm m k = lcm n k

theorem lcm_eq_of_associated_right {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalized_gcd_monoid α] {m n : α} (h : associated m n) (k : α) :

lcm k m = lcm k n

theorem gcd_monoid.prime_of_irreducible {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {x : α} (hi : irreducible x) :

prime x

theorem gcd_monoid.irreducible_iff_prime {α : Type u_1} [cancel_comm_monoid_with_zero α] [gcd_monoid α] {p : α} :

irreducible p ↔ prime p

@[protected, instance]

def normalization_monoid_of_unique_units {α : Type u_1} [cancel_comm_monoid_with_zero α] [unique (units α)] :

normalization_monoid α

Equations

normalization_monoid_of_unique_units = {norm_unit := λ (x : α), 1, norm_unit_zero := _, norm_unit_mul := _, norm_unit_coe_units := _}

@[simp]

theorem norm_unit_eq_one {α : Type u_1} [cancel_comm_monoid_with_zero α] [unique (units α)] (x : α) :

norm_unit x = 1

@[simp]

theorem normalize_eq {α : Type u_1} [cancel_comm_monoid_with_zero α] [unique (units α)] (x : α) :

⇑normalize x = x

@[simp]

theorem associates_equiv_of_unique_units_apply {α : Type u_1} [cancel_comm_monoid_with_zero α] [unique (units α)] (ᾰ : associates α) :

⇑associates_equiv_of_unique_units ᾰ = ᾰ.out

def associates_equiv_of_unique_units {α : Type u_1} [cancel_comm_monoid_with_zero α] [unique (units α)] :

associates α ≃* α

If a monoid's only unit is 1, then it is isomorphic to its associates.

Equations

associates_equiv_of_unique_units = {to_fun := associates.out normalization_monoid_of_unique_units, inv_fun := associates.mk (monoid_with_zero.to_monoid α), left_inv := _, right_inv := _, map_mul' := _}

@[simp]

theorem associates_equiv_of_unique_units_symm_apply {α : Type u_1} [cancel_comm_monoid_with_zero α] [unique (units α)] (a : α) :

⇑(associates_equiv_of_unique_units.symm) a = associates.mk a

theorem gcd_eq_of_dvd_sub_right {α : Type u_1} [comm_ring α] [is_domain α] [normalized_gcd_monoid α] {a b c : α} (h : a ∣ b - c) :

gcd a b = gcd a c

theorem gcd_eq_of_dvd_sub_left {α : Type u_1} [comm_ring α] [is_domain α] [normalized_gcd_monoid α] {a b c : α} (h : a ∣ b - c) :

gcd b a = gcd c a

noncomputable def normalization_monoid_of_monoid_hom_right_inverse {α : Type u_1} [cancel_comm_monoid_with_zero α] [decidable_eq α] (f : associates α →* α) (hinv : function.right_inverse ⇑f associates.mk) :

normalization_monoid α

Define normalization_monoid on a structure from a monoid_hom inverse to associates.mk.

Equations

normalization_monoid_of_monoid_hom_right_inverse f hinv = {norm_unit := λ (a : α), ite (a = 0) 1 (classical.some _), norm_unit_zero := _, norm_unit_mul := _, norm_unit_coe_units := _}

noncomputable def gcd_monoid_of_gcd {α : Type u_1} [cancel_comm_monoid_with_zero α] [decidable_eq α] (gcd : α → α → α) (gcd_dvd_left : ∀ (a b : α), gcd a b ∣ a) (gcd_dvd_right : ∀ (a b : α), gcd a b ∣ b) (dvd_gcd : ∀ {a b c : α}, a ∣ c → a ∣ b → a ∣ gcd c b) :

Define gcd_monoid on a structure just from the gcd and its properties.

Equations

gcd_monoid_of_gcd gcd gcd_dvd_left gcd_dvd_right dvd_gcd = {gcd := gcd, lcm := λ (a b : α), ite (a = 0) 0 (classical.some _), gcd_dvd_left := gcd_dvd_left, gcd_dvd_right := gcd_dvd_right, dvd_gcd := _, gcd_mul_lcm := _, lcm_zero_left := _, lcm_zero_right := _}

noncomputable def normalized_gcd_monoid_of_gcd {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] [decidable_eq α] (gcd : α → α → α) (gcd_dvd_left : ∀ (a b : α), gcd a b ∣ a) (gcd_dvd_right : ∀ (a b : α), gcd a b ∣ b) (dvd_gcd : ∀ {a b c : α}, a ∣ c → a ∣ b → a ∣ gcd c b) (normalize_gcd : ∀ (a b : α), ⇑normalize (gcd a b) = gcd a b) :

Define normalized_gcd_monoid on a structure just from the gcd and its properties.

Equations

normalized_gcd_monoid_of_gcd gcd gcd_dvd_left gcd_dvd_right dvd_gcd normalize_gcd = {to_normalization_monoid := {norm_unit := norm_unit infer_instance, norm_unit_zero := _, norm_unit_mul := _, norm_unit_coe_units := _}, to_gcd_monoid := {gcd := gcd, lcm := λ (a b : α), ite (a = 0) 0 (classical.some _), gcd_dvd_left := gcd_dvd_left, gcd_dvd_right := gcd_dvd_right, dvd_gcd := _, gcd_mul_lcm := _, lcm_zero_left := _, lcm_zero_right := _}, normalize_gcd := normalize_gcd, normalize_lcm := _}

noncomputable def gcd_monoid_of_lcm {α : Type u_1} [cancel_comm_monoid_with_zero α] [decidable_eq α] (lcm : α → α → α) (dvd_lcm_left : ∀ (a b : α), a ∣ lcm a b) (dvd_lcm_right : ∀ (a b : α), b ∣ lcm a b) (lcm_dvd : ∀ {a b c : α}, c ∣ a → b ∣ a → lcm c b ∣ a) :

Define gcd_monoid on a structure just from the lcm and its properties.

Equations

gcd_monoid_of_lcm lcm dvd_lcm_left dvd_lcm_right lcm_dvd = let exists_gcd : ∀ (a b : α), lcm a b ∣ a * b := _ in {gcd := λ (a b : α), ite (a = 0) b (ite (b = 0) a (classical.some _)), lcm := lcm, gcd_dvd_left := _, gcd_dvd_right := _, dvd_gcd := _, gcd_mul_lcm := _, lcm_zero_left := _, lcm_zero_right := _}

noncomputable def normalized_gcd_monoid_of_lcm {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] [decidable_eq α] (lcm : α → α → α) (dvd_lcm_left : ∀ (a b : α), a ∣ lcm a b) (dvd_lcm_right : ∀ (a b : α), b ∣ lcm a b) (lcm_dvd : ∀ {a b c : α}, c ∣ a → b ∣ a → lcm c b ∣ a) (normalize_lcm : ∀ (a b : α), ⇑normalize (lcm a b) = lcm a b) :

Define normalized_gcd_monoid on a structure just from the lcm and its properties.

Equations

normalized_gcd_monoid_of_lcm lcm dvd_lcm_left dvd_lcm_right lcm_dvd normalize_lcm = let exists_gcd : ∀ (a b : α), lcm a b ∣ ⇑normalize (a * b) := _ in {to_normalization_monoid := {norm_unit := norm_unit infer_instance, norm_unit_zero := _, norm_unit_mul := _, norm_unit_coe_units := _}, to_gcd_monoid := {gcd := λ (a b : α), ite (a = 0) (⇑normalize b) (ite (b = 0) (⇑normalize a) (classical.some _)), lcm := lcm, gcd_dvd_left := _, gcd_dvd_right := _, dvd_gcd := _, gcd_mul_lcm := _, lcm_zero_left := _, lcm_zero_right := _}, normalize_gcd := _, normalize_lcm := normalize_lcm}

noncomputable def gcd_monoid_of_exists_gcd {α : Type u_1} [cancel_comm_monoid_with_zero α] [decidable_eq α] (h : ∀ (a b : α), ∃ (c : α), ∀ (d : α), d ∣ a ∧ d ∣ b ↔ d ∣ c) :

Define a gcd_monoid structure on a monoid just from the existence of a gcd.

Equations

gcd_monoid_of_exists_gcd h = gcd_monoid_of_gcd (λ (a b : α), classical.some _) _ _ _

noncomputable def normalized_gcd_monoid_of_exists_gcd {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] [decidable_eq α] (h : ∀ (a b : α), ∃ (c : α), ∀ (d : α), d ∣ a ∧ d ∣ b ↔ d ∣ c) :

Define a normalized_gcd_monoid structure on a monoid just from the existence of a gcd.

Equations

normalized_gcd_monoid_of_exists_gcd h = normalized_gcd_monoid_of_gcd (λ (a b : α), ⇑normalize (classical.some _)) _ _ _ _

noncomputable def gcd_monoid_of_exists_lcm {α : Type u_1} [cancel_comm_monoid_with_zero α] [decidable_eq α] (h : ∀ (a b : α), ∃ (c : α), ∀ (d : α), a ∣ d ∧ b ∣ d ↔ c ∣ d) :

Define a gcd_monoid structure on a monoid just from the existence of an lcm.

Equations

gcd_monoid_of_exists_lcm h = gcd_monoid_of_lcm (λ (a b : α), classical.some _) _ _ _

noncomputable def normalized_gcd_monoid_of_exists_lcm {α : Type u_1} [cancel_comm_monoid_with_zero α] [normalization_monoid α] [decidable_eq α] (h : ∀ (a b : α), ∃ (c : α), ∀ (d : α), a ∣ d ∧ b ∣ d ↔ c ∣ d) :

Define a normalized_gcd_monoid structure on a monoid just from the existence of an lcm.

Equations

normalized_gcd_monoid_of_exists_lcm h = normalized_gcd_monoid_of_lcm (λ (a b : α), ⇑normalize (classical.some _)) _ _ _ _

@[protected, instance]

def comm_group_with_zero.normalized_gcd_monoid (G₀ : Type u_2) [comm_group_with_zero G₀] [decidable_eq G₀] :

normalized_gcd_monoid G₀

Equations

comm_group_with_zero.normalized_gcd_monoid G₀ = {to_normalization_monoid := {norm_unit := λ (x : G₀), dite (x = 0) (λ (h : x = 0), 1) (λ (h : ¬x = 0), (units.mk0 x h)⁻¹), norm_unit_zero := _, norm_unit_mul := _, norm_unit_coe_units := _}, to_gcd_monoid := {gcd := λ (a b : G₀), ite (a = 0 ∧ b = 0) 0 1, lcm := λ (a b : G₀), ite (a = 0 ∨ b = 0) 0 1, gcd_dvd_left := _, gcd_dvd_right := _, dvd_gcd := _, gcd_mul_lcm := _, lcm_zero_left := _, lcm_zero_right := _}, normalize_gcd := _, normalize_lcm := _}

@[simp]

theorem comm_group_with_zero.coe_norm_unit (G₀ : Type u_2) [comm_group_with_zero G₀] [decidable_eq G₀] {a : G₀} (h0 : a ≠ 0) :

↑(norm_unit a) = a⁻¹