Cyclic groups

A group G is called cyclic if there exists an element g : G such that every element of G is of the form g ^ n for some n : ℕ. This file only deals with the predicate on a group to be cyclic. For the concrete cyclic group of order n, see Data.ZMod.Basic.

Main definitions

• IsCyclic is a predicate on a group stating that the group is cyclic.

Main statements

• isCyclic_of_prime_card proves that a finite group of prime order is cyclic.
• isSimpleGroup_of_prime_card, IsSimpleGroup.isCyclic, and IsSimpleGroup.prime_card classify finite simple abelian groups.
• IsCyclic.exponent_eq_card: For a finite cyclic group G, the exponent is equal to the group's cardinality.
• IsCyclic.exponent_eq_zero_of_infinite: Infinite cyclic groups have exponent zero.
• IsCyclic.iff_exponent_eq_card: A finite commutative group is cyclic iff its exponent is equal to its cardinality.

Tags

cyclic group

class IsAddCyclic (α : Type u) [AddGroup α] : Prop

A group is called cyclic if it is generated by a single element.

• exists_generator : ∃ (g : α), ∀ (x : α), x ∈ AddSubgroup.zmultiples g

class IsCyclic (α : Type u) [Group α] : Prop

A group is called cyclic if it is generated by a single element.

• exists_generator : ∃ (g : α), ∀ (x : α), x ∈ Subgroup.zpowers g

instance isAddCyclic_of_subsingleton {α : Type u} [AddGroup α] [Subsingleton α] : IsAddCyclic α

Equations

• (_ : IsAddCyclic α) = (_ : IsAddCyclic α)

instance isCyclic_of_subsingleton {α : Type u} [Group α] [Subsingleton α] : IsCyclic α

Equations

• (_ : IsCyclic α) = (_ : IsCyclic α)

@[simp]

theorem isCyclic_multiplicative_iff {α : Type u} [AddGroup α] : IsCyclic (Multiplicative α) ↔ IsAddCyclic α

instance isCyclic_multiplicative {α : Type u} [AddGroup α] [IsAddCyclic α] : IsCyclic (Multiplicative α)

Equations

• (_ : IsCyclic (Multiplicative α)) = (_ : IsCyclic (Multiplicative α))

@[simp]

theorem isAddCyclic_additive_iff {α : Type u} [Group α] : IsAddCyclic (Additive α) ↔ IsCyclic α

instance isAddCyclic_additive {α : Type u} [Group α] [IsCyclic α] : IsAddCyclic (Additive α)

Equations

• (_ : IsAddCyclic (Additive α)) = (_ : IsAddCyclic (Additive α))

theorem IsAddCyclic.addCommGroup.proof_1 {α : Type u_1} [hg : AddGroup α] [IsAddCyclic α] (x : α) (y : α) : x + y = y + x

abbrev IsAddCyclic.addCommGroup.match_1 {α : Type u_1} [hg : AddGroup α] (y : α) : ∀ (w : α) (motive : y ∈ AddSubgroup.zmultiples w → Prop) (x : y ∈ AddSubgroup.zmultiples w), (∀ (w_1 : ℤ) (hm : (fun (x : ℤ) => x • w) w_1 = y), motive (_ : ∃ (y_1 : ℤ), (fun (x : ℤ) => x • w) y_1 = y)) → motive x

Equations

• (_ : motive x) = (_ : motive x)

def IsAddCyclic.addCommGroup {α : Type u} [hg : AddGroup α] [IsAddCyclic α] : AddCommGroup α

A cyclic group is always commutative. This is not an instance because often we have a better proof of AddCommGroup.

Equations

• IsAddCyclic.addCommGroup = AddCommGroup.mk (_ : ∀ (x y : α), x + y = y + x)

abbrev IsAddCyclic.addCommGroup.match_2 {α : Type u_1} [hg : AddGroup α] (motive : (∃ (g : α), ∀ (x : α), x ∈ AddSubgroup.zmultiples g) → Prop) : ∀ (x : ∃ (g : α), ∀ (x : α), x ∈ AddSubgroup.zmultiples g), (∀ (w : α) (hg_1 : ∀ (x : α), x ∈ AddSubgroup.zmultiples w), motive (_ : ∃ (g : α), ∀ (x : α), x ∈ AddSubgroup.zmultiples g)) → motive x

Equations

• (_ : motive x) = (_ : motive x)

def IsCyclic.commGroup {α : Type u} [hg : Group α] [IsCyclic α] : CommGroup α

A cyclic group is always commutative. This is not an instance because often we have a better proof of CommGroup.

Equations

• IsCyclic.commGroup = CommGroup.mk (_ : ∀ (x y : α), x * y = y * x)

theorem Nontrivial.of_not_isAddCyclic {α : Type u} [AddGroup α] (nc : ¬IsAddCyclic α) : Nontrivial α

A non-cyclic additive group is non-trivial.

theorem Nontrivial.of_not_isCyclic {α : Type u} [Group α] (nc : ¬IsCyclic α) : Nontrivial α

A non-cyclic multiplicative group is non-trivial.

theorem MonoidAddHom.map_add_cyclic {G : Type u_1} [AddGroup G] [h : IsAddCyclic G] (σ : G →+ G) : ∃ (m : ℤ), ∀ (g : G), σ g = m • g

theorem MonoidHom.map_cyclic {G : Type u_1} [Group G] [h : IsCyclic G] (σ : G →* G) : ∃ (m : ℤ), ∀ (g : G), σ g = g ^ m

theorem isAddCyclic_of_orderOf_eq_card {α : Type u} [AddGroup α] [Fintype α] (x : α) (hx : addOrderOf x = Fintype.card α) : IsAddCyclic α

theorem isCyclic_of_orderOf_eq_card {α : Type u} [Group α] [Fintype α] (x : α) (hx : orderOf x = Fintype.card α) : IsCyclic α

theorem isAddCyclic_of_prime_card {α : Type u} [AddGroup α] [Fintype α] {p : ℕ} [hp : Fact (Nat.Prime p)] (h : Fintype.card α = p) : IsAddCyclic α

A finite group of prime order is cyclic.

theorem isCyclic_of_prime_card {α : Type u} [Group α] [Fintype α] {p : ℕ} [hp : Fact (Nat.Prime p)] (h : Fintype.card α = p) : IsCyclic α

A finite group of prime order is cyclic.

theorem isAddCyclic_of_surjective {H : Type u_1} {G : Type u_2} {F : Type u_3} [AddGroup H] [AddGroup G] [hH : IsAddCyclic H] [AddMonoidHomClass F H G] (f : F) (hf : Function.Surjective ⇑f) : IsAddCyclic G

theorem isCyclic_of_surjective {H : Type u_1} {G : Type u_2} {F : Type u_3} [Group H] [Group G] [hH : IsCyclic H] [MonoidHomClass F H G] (f : F) (hf : Function.Surjective ⇑f) : IsCyclic G

theorem addOrderOf_eq_card_of_forall_mem_zmultiples {α : Type u} [AddGroup α] [Fintype α] {g : α} (hx : ∀ (x : α), x ∈ AddSubgroup.zmultiples g) : addOrderOf g = Fintype.card α

theorem orderOf_eq_card_of_forall_mem_zpowers {α : Type u} [Group α] [Fintype α] {g : α} (hx : ∀ (x : α), x ∈ Subgroup.zpowers g) : orderOf g = Fintype.card α

theorem exists_nsmul_ne_zero_of_isAddCyclic {G : Type u_1} [AddGroup G] [Fintype G] [G_cyclic : IsAddCyclic G] {k : ℕ} (k_pos : k ≠ 0) (k_lt_card_G : k < Fintype.card G) : ∃ (a : G), k • a ≠ 0

theorem exists_pow_ne_one_of_isCyclic {G : Type u_1} [Group G] [Fintype G] [G_cyclic : IsCyclic G] {k : ℕ} (k_pos : k ≠ 0) (k_lt_card_G : k < Fintype.card G) : ∃ (a : G), a ^ k ≠ 1

theorem Infinite.addOrderOf_eq_zero_of_forall_mem_zmultiples {α : Type u} [AddGroup α] [Infinite α] {g : α} (h : ∀ (x : α), x ∈ AddSubgroup.zmultiples g) : addOrderOf g = 0

theorem Infinite.orderOf_eq_zero_of_forall_mem_zpowers {α : Type u} [Group α] [Infinite α] {g : α} (h : ∀ (x : α), x ∈ Subgroup.zpowers g) : orderOf g = 0

instance Bot.isAddCyclic {α : Type u} [AddGroup α] : IsAddCyclic ↥⊥

Equations

• (_ : IsAddCyclic ↥⊥) = (_ : IsAddCyclic ↥⊥)

instance Bot.isCyclic {α : Type u} [Group α] : IsCyclic ↥⊥

Equations

• (_ : IsCyclic ↥⊥) = (_ : IsCyclic ↥⊥)

abbrev AddSubgroup.isAddCyclic.match_1 {α : Type u_1} [AddGroup α] (g : α) (x : α) (motive : x ∈ AddSubgroup.zmultiples g → Prop) : ∀ (x_1 : x ∈ AddSubgroup.zmultiples g), (∀ (k : ℤ) (hk : (fun (x : ℤ) => x • g) k = x), motive (_ : ∃ (y : ℤ), (fun (x : ℤ) => x • g) y = x)) → motive x_1

Equations

• (_ : motive x) = (_ : motive x)

abbrev AddSubgroup.isAddCyclic.match_3 {α : Type u_1} [AddGroup α] (H : AddSubgroup α) (motive : (∃ x ∈ H, x ≠ 0) → Prop) : ∀ (hx : ∃ x ∈ H, x ≠ 0), (∀ (x : α) (hx₁ : x ∈ H) (hx₂ : x ≠ 0), motive (_ : ∃ x ∈ H, x ≠ 0)) → motive hx

Equations

• (_ : motive hx) = (_ : motive hx)

abbrev AddSubgroup.isAddCyclic.match_2 {α : Type u_1} [AddGroup α] (H : AddSubgroup α) (motive : ↥H → Prop) : ∀ (x : ↥H), (∀ (x : α) (hx : x ∈ H), motive { val := x, property := hx }) → motive x

Equations

• (_ : motive x) = (_ : motive x)

instance AddSubgroup.isAddCyclic {α : Type u} [AddGroup α] [IsAddCyclic α] (H : AddSubgroup α) : IsAddCyclic ↥H

Equations

• (_ : IsAddCyclic ↥H) = (_ : IsAddCyclic ↥H)

instance Subgroup.isCyclic {α : Type u} [Group α] [IsCyclic α] (H : Subgroup α) : IsCyclic ↥H

Equations

• (_ : IsCyclic ↥H) = (_ : IsCyclic ↥H)

abbrev IsAddCyclic.card_pow_eq_one_le.match_1 {α : Type u_1} [AddGroup α] (g : α) (x : α) (motive : x ∈ AddSubmonoid.multiples g → Prop) : ∀ (x_1 : x ∈ AddSubmonoid.multiples g), (∀ (m : ℕ) (hm : (fun (x : ℕ) => x • g) m = x), motive (_ : ∃ (y : ℕ), (fun (x : ℕ) => x • g) y = x)) → motive x_1

Equations

• (_ : motive x) = (_ : motive x)

theorem IsAddCyclic.card_pow_eq_one_le {α : Type u} [AddGroup α] [DecidableEq α] [Fintype α] [IsAddCyclic α] {n : ℕ} (hn0 : 0 < n) : (Finset.filter (fun (a : α) => n • a = 0) Finset.univ).card ≤ n

abbrev IsAddCyclic.card_pow_eq_one_le.match_2 {α : Type u_1} [Fintype α] {n : ℕ} (motive : Nat.gcd n (Fintype.card α) ∣ Fintype.card α → Prop) : ∀ (x : Nat.gcd n (Fintype.card α) ∣ Fintype.card α), (∀ (m : ℕ) (hm : Fintype.card α = Nat.gcd n (Fintype.card α) * m), motive (_ : ∃ (c : ℕ), Fintype.card α = Nat.gcd n (Fintype.card α) * c)) → motive x

Equations

• (_ : motive x) = (_ : motive x)

theorem IsCyclic.card_pow_eq_one_le {α : Type u} [Group α] [DecidableEq α] [Fintype α] [IsCyclic α] {n : ℕ} (hn0 : 0 < n) : (Finset.filter (fun (a : α) => a ^ n = 1) Finset.univ).card ≤ n

theorem IsAddCyclic.exists_addMonoid_generator {α : Type u} [AddGroup α] [Finite α] [IsAddCyclic α] : ∃ (x : α), ∀ (y : α), y ∈ AddSubmonoid.multiples x

theorem IsCyclic.exists_monoid_generator {α : Type u} [Group α] [Finite α] [IsCyclic α] : ∃ (x : α), ∀ (y : α), y ∈ Submonoid.powers x

theorem IsAddCyclic.image_range_addOrderOf {α : Type u} {a : α} [AddGroup α] [DecidableEq α] [Fintype α] (ha : ∀ (x : α), x ∈ AddSubgroup.zmultiples a) : Finset.image (fun (i : ℕ) => i • a) (Finset.range (addOrderOf a)) = Finset.univ

theorem IsCyclic.image_range_orderOf {α : Type u} {a : α} [Group α] [DecidableEq α] [Fintype α] (ha : ∀ (x : α), x ∈ Subgroup.zpowers a) : Finset.image (fun (i : ℕ) => a ^ i) (Finset.range (orderOf a)) = Finset.univ

theorem IsAddCyclic.image_range_card {α : Type u} {a : α} [AddGroup α] [DecidableEq α] [Fintype α] (ha : ∀ (x : α), x ∈ AddSubgroup.zmultiples a) : Finset.image (fun (i : ℕ) => i • a) (Finset.range (Fintype.card α)) = Finset.univ

theorem IsCyclic.image_range_card {α : Type u} {a : α} [Group α] [DecidableEq α] [Fintype α] (ha : ∀ (x : α), x ∈ Subgroup.zpowers a) : Finset.image (fun (i : ℕ) => a ^ i) (Finset.range (Fintype.card α)) = Finset.univ

theorem card_orderOf_eq_totient_aux₂ {α : Type u} [Group α] [DecidableEq α] [Fintype α] (hn : ∀ (n : ℕ), 0 < n → (Finset.filter (fun (a : α) => a ^ n = 1) Finset.univ).card ≤ n) {d : ℕ} (hd : d ∣ Fintype.card α) : (Finset.filter (fun (a : α) => orderOf a = d) Finset.univ).card = Nat.totient d

theorem isCyclic_of_card_pow_eq_one_le {α : Type u} [Group α] [DecidableEq α] [Fintype α] (hn : ∀ (n : ℕ), 0 < n → (Finset.filter (fun (a : α) => a ^ n = 1) Finset.univ).card ≤ n) : IsCyclic α

theorem isAddCyclic_of_card_pow_eq_one_le {α : Type u_1} [AddGroup α] [DecidableEq α] [Fintype α] (hn : ∀ (n : ℕ), 0 < n → (Finset.filter (fun (a : α) => n • a = 0) Finset.univ).card ≤ n) : IsAddCyclic α

theorem IsCyclic.card_orderOf_eq_totient {α : Type u} [Group α] [IsCyclic α] [Fintype α] {d : ℕ} (hd : d ∣ Fintype.card α) : (Finset.filter (fun (a : α) => orderOf a = d) Finset.univ).card = Nat.totient d

theorem IsAddCyclic.card_orderOf_eq_totient {α : Type u_1} [AddGroup α] [IsAddCyclic α] [Fintype α] {d : ℕ} (hd : d ∣ Fintype.card α) : (Finset.filter (fun (a : α) => addOrderOf a = d) Finset.univ).card = Nat.totient d

theorem isSimpleAddGroup_of_prime_card {α : Type u} [AddGroup α] [Fintype α] {p : ℕ} [hp : Fact (Nat.Prime p)] (h : Fintype.card α = p) : IsSimpleAddGroup α

A finite group of prime order is simple.

theorem isSimpleGroup_of_prime_card {α : Type u} [Group α] [Fintype α] {p : ℕ} [hp : Fact (Nat.Prime p)] (h : Fintype.card α = p) : IsSimpleGroup α

A finite group of prime order is simple.

theorem commutative_of_add_cyclic_center_quotient {G : Type u_1} {H : Type u_2} [AddGroup G] [AddGroup H] [IsAddCyclic H] (f : G →+ H) (hf : AddMonoidHom.ker f ≤ AddSubgroup.center G) (a : G) (b : G) : a + b = b + a

A group is commutative if the quotient by the center is cyclic. Also see addCommGroup_of_cycle_center_quotient for the AddCommGroup instance.

abbrev commutative_of_add_cyclic_center_quotient.match_1 {G : Type u_2} {H : Type u_1} [AddGroup G] [AddGroup H] (f : G →+ H) (b : G) (x : H) (y : G) (hxy : f y = x) (motive : { val := f b, property := (_ : ∃ (y : G), f y = f b) } ∈ AddSubgroup.zmultiples { val := x, property := (_ : ∃ (y : G), f y = x) } → Prop) : ∀ (x_1 : { val := f b, property := (_ : ∃ (y : G), f y = f b) } ∈ AddSubgroup.zmultiples { val := x, property := (_ : ∃ (y : G), f y = x) }), (∀ (n : ℤ) (hn : (fun (x_2 : ℤ) => x_2 • { val := x, property := (_ : ∃ (y : G), f y = x) }) n = { val := f b, property := (_ : ∃ (y : G), f y = f b) }), motive (_ : ∃ (y_1 : ℤ), (fun (x_2 : ℤ) => x_2 • { val := x, property := (_ : ∃ (y : G), f y = x) }) y_1 = { val := f b, property := (_ : ∃ (y : G), f y = f b) })) → motive x_1

Equations

• (_ : motive x) = (_ : motive x)

abbrev commutative_of_add_cyclic_center_quotient.match_2 {G : Type u_2} {H : Type u_1} [AddGroup G] [AddGroup H] (f : G →+ H) (motive : (∃ (g : ↥(AddMonoidHom.range f)), ∀ (x : ↥(AddMonoidHom.range f)), x ∈ AddSubgroup.zmultiples g) → Prop) : ∀ (x : ∃ (g : ↥(AddMonoidHom.range f)), ∀ (x : ↥(AddMonoidHom.range f)), x ∈ AddSubgroup.zmultiples g), (∀ (x : H) (y : G) (hxy : f y = x) (hx : ∀ (a : ↥(AddMonoidHom.range f)), a ∈ AddSubgroup.zmultiples { val := x, property := (_ : ∃ (y : G), f y = x) }), motive (_ : ∃ (g : ↥(AddMonoidHom.range f)), ∀ (x : ↥(AddMonoidHom.range f)), x ∈ AddSubgroup.zmultiples g)) → motive x

Equations

• (_ : motive x) = (_ : motive x)

theorem commutative_of_cyclic_center_quotient {G : Type u_1} {H : Type u_2} [Group G] [Group H] [IsCyclic H] (f : G →* H) (hf : MonoidHom.ker f ≤ Subgroup.center G) (a : G) (b : G) : a * b = b * a

A group is commutative if the quotient by the center is cyclic. Also see commGroup_of_cycle_center_quotient for the CommGroup instance.

def commutativeOfAddCycleCenterQuotient {G : Type u_1} {H : Type u_2} [AddGroup G] [AddGroup H] [IsAddCyclic H] (f : G →+ H) (hf : AddMonoidHom.ker f ≤ AddSubgroup.center G) : AddCommGroup G

A group is commutative if the quotient by the center is cyclic.

Equations

• commutativeOfAddCycleCenterQuotient f hf = let src := let_fun this := inferInstance; this; AddCommGroup.mk (_ : ∀ (a b : G), a + b = b + a)

def commGroupOfCycleCenterQuotient {G : Type u_1} {H : Type u_2} [Group G] [Group H] [IsCyclic H] (f : G →* H) (hf : MonoidHom.ker f ≤ Subgroup.center G) : CommGroup G

A group is commutative if the quotient by the center is cyclic.

Equations

• commGroupOfCycleCenterQuotient f hf = let src := let_fun this := inferInstance; this; CommGroup.mk (_ : ∀ (a b : G), a * b = b * a)

instance IsSimpleAddGroup.isAddCyclic {α : Type u} [AddCommGroup α] [IsSimpleAddGroup α] : IsAddCyclic α

Equations

• (_ : IsAddCyclic α) = (_ : IsAddCyclic α)

instance IsSimpleGroup.isCyclic {α : Type u} [CommGroup α] [IsSimpleGroup α] : IsCyclic α

Equations

• (_ : IsCyclic α) = (_ : IsCyclic α)

theorem IsSimpleAddGroup.prime_card {α : Type u} [AddCommGroup α] [IsSimpleAddGroup α] [Fintype α] : Nat.Prime (Fintype.card α)

theorem IsSimpleGroup.prime_card {α : Type u} [CommGroup α] [IsSimpleGroup α] [Fintype α] : Nat.Prime (Fintype.card α)

theorem AddCommGroup.is_simple_iff_isAddCyclic_and_prime_card {α : Type u} [Fintype α] [AddCommGroup α] : IsSimpleAddGroup α ↔ IsAddCyclic α ∧ Nat.Prime (Fintype.card α)

theorem CommGroup.is_simple_iff_isCyclic_and_prime_card {α : Type u} [Fintype α] [CommGroup α] : IsSimpleGroup α ↔ IsCyclic α ∧ Nat.Prime (Fintype.card α)

instance instIsAddCyclicIntInstAddGroupInt : IsAddCyclic ℤ

Equations

• instIsAddCyclicIntInstAddGroupInt = (_ : IsAddCyclic ℤ)

instance ZMod.instIsAddCyclic (n : ℕ) : IsAddCyclic (ZMod n)

Equations

• (_ : IsAddCyclic (ZMod n)) = (_ : IsAddCyclic (ZMod n))

instance ZMod.instIsSimpleAddGroup {p : ℕ} [Fact (Nat.Prime p)] : IsSimpleAddGroup (ZMod p)

Equations

• (_ : IsSimpleAddGroup (ZMod p)) = (_ : IsSimpleAddGroup (ZMod p))

theorem IsAddCyclic.exponent_eq_card {α : Type u} [AddGroup α] [IsAddCyclic α] [Fintype α] : AddMonoid.exponent α = Fintype.card α

theorem IsCyclic.exponent_eq_card {α : Type u} [Group α] [IsCyclic α] [Fintype α] : Monoid.exponent α = Fintype.card α

abbrev IsAddCyclic.of_exponent_eq_card.match_1 {α : Type u_1} [AddCommGroup α] [Fintype α] (motive : (∃ a ∈ Finset.univ, addOrderOf a = Finset.max' (Finset.image (fun (g : α) => addOrderOf g) Finset.univ) (_ : ∃ (x : ℕ), x ∈ Finset.image addOrderOf Finset.univ)) → Prop) : ∀ (x : ∃ a ∈ Finset.univ, addOrderOf a = Finset.max' (Finset.image (fun (g : α) => addOrderOf g) Finset.univ) (_ : ∃ (x : ℕ), x ∈ Finset.image addOrderOf Finset.univ)), (∀ (g : α) (left : g ∈ Finset.univ) (hg : addOrderOf g = Finset.max' (Finset.image (fun (g : α) => addOrderOf g) Finset.univ) (_ : ∃ (x : ℕ), x ∈ Finset.image addOrderOf Finset.univ)), motive (_ : ∃ a ∈ Finset.univ, addOrderOf a = Finset.max' (Finset.image (fun (g : α) => addOrderOf g) Finset.univ) (_ : ∃ (x : ℕ), x ∈ Finset.image addOrderOf Finset.univ))) → motive x

Equations

• (_ : motive x) = (_ : motive x)

theorem IsAddCyclic.of_exponent_eq_card {α : Type u} [AddCommGroup α] [Fintype α] (h : AddMonoid.exponent α = Fintype.card α) : IsAddCyclic α

theorem IsCyclic.of_exponent_eq_card {α : Type u} [CommGroup α] [Fintype α] (h : Monoid.exponent α = Fintype.card α) : IsCyclic α

theorem IsAddCyclic.iff_exponent_eq_card {α : Type u} [AddCommGroup α] [Fintype α] : IsAddCyclic α ↔ AddMonoid.exponent α = Fintype.card α

theorem IsCyclic.iff_exponent_eq_card {α : Type u} [CommGroup α] [Fintype α] : IsCyclic α ↔ Monoid.exponent α = Fintype.card α

theorem IsAddCyclic.exponent_eq_zero_of_infinite {α : Type u} [AddGroup α] [IsAddCyclic α] [Infinite α] : AddMonoid.exponent α = 0

theorem IsCyclic.exponent_eq_zero_of_infinite {α : Type u} [Group α] [IsCyclic α] [Infinite α] : Monoid.exponent α = 0

@[simp]

theorem ZMod.exponent (n : ℕ) : AddMonoid.exponent (ZMod n) = n

theorem not_isAddCyclic_iff_exponent_eq_prime {α : Type u} [AddGroup α] {p : ℕ} (hp : Nat.Prime p) (hα : Nat.card α = p ^ 2) : ¬IsAddCyclic α ↔ AddMonoid.exponent α = p

theorem not_isCyclic_iff_exponent_eq_prime {α : Type u} [Group α] {p : ℕ} (hp : Nat.Prime p) (hα : Nat.card α = p ^ 2) : ¬IsCyclic α ↔ Monoid.exponent α = p

A group of order p ^ 2 is not cyclic if and only if its exponent is p.