E : ℕ → Type u_1
x y z : (n : ℕ) → E n
h : x ≠ z
H : firstDiff x z < min (firstDiff x y) (firstDiff y z)
⊢ False
E : ℕ → Type u_1
x y z : (n : ℕ) → E n
h : x ≠ z
⊢ min (firstDiff x y) (firstDiff y z) ≤ firstDiff x z
by_contra' H
E : ℕ → Type u_1
x y z : (n : ℕ) → E n
h : x ≠ z
H : firstDiff x z < firstDiff x y ∧ firstDiff x z < firstDiff y z
⊢ False
E : ℕ → Type u_1
x y z : (n : ℕ) → E n
h : x ≠ z
H : firstDiff x z < min (firstDiff x y) (firstDiff y z)
⊢ False
rw [lt_min_iff] at H
E : ℕ → Type u_1
x y z : (n : ℕ) → E n
h : x ≠ z
H : firstDiff x z < firstDiff x y ∧ firstDiff x z < firstDiff y z
⊢ x (firstDiff x z) = z (firstDiff x z)
E : ℕ → Type u_1
x y z : (n : ℕ) → E n
h : x ≠ z
H : firstDiff x z < firstDiff x y ∧ firstDiff x z < firstDiff y z
⊢ False
refine apply_firstDiff_ne h ?_
no goals
E : ℕ → Type u_1
x y z : (n : ℕ) → E n
h : x ≠ z
H : firstDiff x z < firstDiff x y ∧ firstDiff x z < firstDiff y z
⊢ x (firstDiff x z) = z (firstDiff x z)
calc
  x (firstDiff x z) = y (firstDiff x z) := apply_eq_of_lt_firstDiff H.1
  _ = z (firstDiff x z) := apply_eq_of_lt_firstDiff H.2