N✝ : ℕ
N : ℕ+
⊢ Gamma ↑N ≤ Gamma1 ↑N
N✝ : ℕ
N : ℕ+
⊢ IsCongruenceSubgroup (Gamma1 ↑N)
refine' ⟨N, _⟩
N✝ : ℕ
N : ℕ+
A : SL(2, ℤ)
hA : A ∈ Gamma ↑N
⊢ A ∈ Gamma1 ↑N
N✝ : ℕ
N : ℕ+
⊢ Gamma ↑N ≤ Gamma1 ↑N
intro A hA
N✝ : ℕ
N : ℕ+
A : SL(2, ℤ)
hA : ↑(↑A 0 0) = 1 ∧ ↑(↑A 0 1) = 0 ∧ ↑(↑A 1 0) = 0 ∧ ↑(↑A 1 1) = 1
⊢ ↑(↑A 0 0) = 1 ∧ ↑(↑A 1 1) = 1 ∧ ↑(↑A 1 0) = 0
N✝ : ℕ
N : ℕ+
A : SL(2, ℤ)
hA : A ∈ Gamma ↑N
⊢ A ∈ Gamma1 ↑N
simp only [Gamma1_mem, Gamma_mem] at *
no goals
N✝ : ℕ
N : ℕ+
A : SL(2, ℤ)
hA : ↑(↑A 0 0) = 1 ∧ ↑(↑A 0 1) = 0 ∧ ↑(↑A 1 0) = 0 ∧ ↑(↑A 1 1) = 1
⊢ ↑(↑A 0 0) = 1 ∧ ↑(↑A 1 1) = 1 ∧ ↑(↑A 1 0) = 0
simp only [hA, eq_self_iff_true, and_self_iff]