Theorem: Subgroup.card_commutator_le_of_finite_commutatorSet
File: Mathlib/GroupTheory/Schreier.lean

Proof steps:
state_before: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
state_after: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤
    Nat.card ↑(commutatorSet ↥(closureCommutatorRepresentatives G)) ^ Group.rank ↥(closureCommutatorRepresentatives G)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
tactic: have h1 := index_center_le_pow (closureCommutatorRepresentatives G)
state_before: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤
    Nat.card ↑(commutatorSet ↥(closureCommutatorRepresentatives G)) ^ Group.rank ↥(closureCommutatorRepresentatives G)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
state_after: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤
    Nat.card ↑(commutatorSet ↥(closureCommutatorRepresentatives G)) ^ Group.rank ↥(closureCommutatorRepresentatives G)
h2 :
  Nat.card ↥(_root_.commutator ↥(closureCommutatorRepresentatives G)) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      ((center ↥(closureCommutatorRepresentatives G)).index *
          Nat.card ↑(commutatorSet ↥(closureCommutatorRepresentatives G)) +
        1)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
tactic: have h2 := card_commutator_dvd_index_center_pow (closureCommutatorRepresentatives G)
state_before: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤
    Nat.card ↑(commutatorSet ↥(closureCommutatorRepresentatives G)) ^ Group.rank ↥(closureCommutatorRepresentatives G)
h2 :
  Nat.card ↥(_root_.commutator ↥(closureCommutatorRepresentatives G)) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      ((center ↥(closureCommutatorRepresentatives G)).index *
          Nat.card ↑(commutatorSet ↥(closureCommutatorRepresentatives G)) +
        1)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
state_after: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤
    Nat.card ↑(commutatorSet G) ^ Group.rank ↥(closureCommutatorRepresentatives G)
h2 :
  Nat.card ↥(_root_.commutator ↥(closureCommutatorRepresentatives G)) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      ((center ↥(closureCommutatorRepresentatives G)).index * Nat.card ↑(commutatorSet G) + 1)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
tactic: rw [card_commutatorSet_closureCommutatorRepresentatives] at h1 h2
state_before: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤
    Nat.card ↑(commutatorSet G) ^ Group.rank ↥(closureCommutatorRepresentatives G)
h2 :
  Nat.card ↥(_root_.commutator ↥(closureCommutatorRepresentatives G)) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      ((center ↥(closureCommutatorRepresentatives G)).index * Nat.card ↑(commutatorSet G) + 1)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
state_after: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤
    Nat.card ↑(commutatorSet G) ^ Group.rank ↥(closureCommutatorRepresentatives G)
h2 :
  Nat.card ↥(_root_.commutator G) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      ((center ↥(closureCommutatorRepresentatives G)).index * Nat.card ↑(commutatorSet G) + 1)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
tactic: rw [card_commutator_closureCommutatorRepresentatives] at h2
state_before: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤
    Nat.card ↑(commutatorSet G) ^ Group.rank ↥(closureCommutatorRepresentatives G)
h2 :
  Nat.card ↥(_root_.commutator G) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      ((center ↥(closureCommutatorRepresentatives G)).index * Nat.card ↑(commutatorSet G) + 1)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
state_after: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h2 :
  Nat.card ↥(_root_.commutator G) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      ((center ↥(closureCommutatorRepresentatives G)).index * Nat.card ↑(commutatorSet G) + 1)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤ Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G))
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
tactic: replace h1 :=
    h1.trans
      (Nat.pow_le_pow_of_le_right Finite.card_pos (rank_closureCommutatorRepresentatives_le G))
state_before: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h2 :
  Nat.card ↥(_root_.commutator G) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      ((center ↥(closureCommutatorRepresentatives G)).index * Nat.card ↑(commutatorSet G) + 1)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤ Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G))
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
state_after: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤ Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G))
h2 :
  Nat.card ↥(_root_.commutator G) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      (Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G)) * Nat.card ↑(commutatorSet G) + 1)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
tactic: replace h2 := h2.trans (pow_dvd_pow _ (add_le_add_right (mul_le_mul_right' h1 _) 1))
state_before: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤ Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G))
h2 :
  Nat.card ↥(_root_.commutator G) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      (Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G)) * Nat.card ↑(commutatorSet G) + 1)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
state_after: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤ Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G))
h2 :
  Nat.card ↥(_root_.commutator G) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      (Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G) + 1) + 1)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
tactic: rw [← pow_succ] at h2
state_before: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤ Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G))
h2 :
  Nat.card ↥(_root_.commutator G) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      (Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G) + 1) + 1)
⊢ Nat.card ↥(_root_.commutator G) ≤ cardCommutatorBound (Nat.card ↑(commutatorSet G))
state_after: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤ Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G))
h2 :
  Nat.card ↥(_root_.commutator G) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      (Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G) + 1) + 1)
⊢ 0 <
    (center ↥(closureCommutatorRepresentatives G)).index ^
      (Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G) + 1) + 1)
tactic: refine (Nat.le_of_dvd ?_ h2).trans (Nat.pow_le_pow_left h1 _)
state_before: G : Type u_1
inst✝¹ : Group G
H : Subgroup G
R S : Set G
inst✝ : Finite ↑(commutatorSet G)
h1 :
  (center ↥(closureCommutatorRepresentatives G)).index ≤ Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G))
h2 :
  Nat.card ↥(_root_.commutator G) ∣
    (center ↥(closureCommutatorRepresentatives G)).index ^
      (Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G) + 1) + 1)
⊢ 0 <
    (center ↥(closureCommutatorRepresentatives G)).index ^
      (Nat.card ↑(commutatorSet G) ^ (2 * Nat.card ↑(commutatorSet G) + 1) + 1)
state_after: no goals
tactic: exact pow_pos (Nat.pos_of_ne_zero FiniteIndex.finiteIndex) _