-- Mathlib/Algebra/ContinuedFractions/Computation/Translations.lean
theorem of_s_succ (n : ℕ) : (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Proof state:
case inr.inr.intro.intro.intro
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
h₁ : (of (fract v)⁻¹).s.get? n ≠ none
p : Pair K
hp : (of (fract v)⁻¹).s.get? n = some p
p' : IntFractPair K
hp'₁ : IntFractPair.stream v (n + 1 + 1) = some p'
right✝ : ↑p'.b = p.b
Hp : (of (fract v)⁻¹).s.get? n = some { a := 1, b := ↑p'.b }
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Tactic:
rw [Hp, get?_of_eq_some_of_succ_get?_intFractPair_stream hp'₁]

Result:
no goals

Proof state:
case inr.inr.intro
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
h₁ : (of (fract v)⁻¹).s.get? n ≠ none
p : Pair K
hp : (of (fract v)⁻¹).s.get? n = some p
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Tactic:
obtain ⟨p', hp'₁, _⟩ := exists_succ_get?_stream_of_gcf_of_get?_eq_some hp

Result:
case inr.inr.intro.intro.intro
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
h₁ : (of (fract v)⁻¹).s.get? n ≠ none
p : Pair K
hp : (of (fract v)⁻¹).s.get? n = some p
p' : IntFractPair K
hp'₁ : IntFractPair.stream (fract v)⁻¹ (n + 1) = some p'
right✝ : ↑p'.b = p.b
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Proof state:
case inr.inr.intro.intro.intro
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
h₁ : (of (fract v)⁻¹).s.get? n ≠ none
p : Pair K
hp : (of (fract v)⁻¹).s.get? n = some p
p' : IntFractPair K
hp'₁ : IntFractPair.stream (fract v)⁻¹ (n + 1) = some p'
right✝ : ↑p'.b = p.b
Hp : (of (fract v)⁻¹).s.get? n = some { a := 1, b := ↑p'.b }
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Tactic:
rw [← stream_succ h] at hp'₁

Result:
case inr.inr.intro.intro.intro
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
h₁ : (of (fract v)⁻¹).s.get? n ≠ none
p : Pair K
hp : (of (fract v)⁻¹).s.get? n = some p
p' : IntFractPair K
hp'₁ : IntFractPair.stream v (n + 1 + 1) = some p'
right✝ : ↑p'.b = p.b
Hp : (of (fract v)⁻¹).s.get? n = some { a := 1, b := ↑p'.b }
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Proof state:
case inr.inr
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
h₁ : (of (fract v)⁻¹).s.get? n ≠ none
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Tactic:
obtain ⟨p, hp⟩ := Option.ne_none_iff_exists'.mp h₁

Result:
case inr.inr.intro
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
h₁ : (of (fract v)⁻¹).s.get? n ≠ none
p : Pair K
hp : (of (fract v)⁻¹).s.get? n = some p
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Proof state:
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Tactic:
rcases eq_or_ne (fract v) 0 with h | h

Result:
case inl
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v = 0
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

case inr
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Proof state:
case inr.inr.intro.intro.intro
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
h₁ : (of (fract v)⁻¹).s.get? n ≠ none
p : Pair K
hp : (of (fract v)⁻¹).s.get? n = some p
p' : IntFractPair K
hp'₁ : IntFractPair.stream (fract v)⁻¹ (n + 1) = some p'
right✝ : ↑p'.b = p.b
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Tactic:
have Hp := get?_of_eq_some_of_succ_get?_intFractPair_stream hp'₁

Result:
case inr.inr.intro.intro.intro
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
h₁ : (of (fract v)⁻¹).s.get? n ≠ none
p : Pair K
hp : (of (fract v)⁻¹).s.get? n = some p
p' : IntFractPair K
hp'₁ : IntFractPair.stream (fract v)⁻¹ (n + 1) = some p'
right✝ : ↑p'.b = p.b
Hp : (of (fract v)⁻¹).s.get? n = some { a := 1, b := ↑p'.b }
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Proof state:
case inl.intro
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
n : ℕ
a : ℤ
h : fract ↑a = 0
⊢ (of ↑a).s.get? (n + 1) = (of (fract ↑a)⁻¹).s.get? n

Tactic:
rw [fract_intCast, inv_zero, of_s_of_int, ← cast_zero, of_s_of_int,
  Stream'.Seq.get?_nil, Stream'.Seq.get?_nil]

Result:
no goals

Proof state:
case inl
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v = 0
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Tactic:
obtain ⟨a, rfl⟩ : ∃ a : ℤ, v = a := ⟨⌊v⌋, eq_of_sub_eq_zero h⟩

Result:
case inl.intro
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
n : ℕ
a : ℤ
h : fract ↑a = 0
⊢ (of ↑a).s.get? (n + 1) = (of (fract ↑a)⁻¹).s.get? n

Proof state:
case inr.inl
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
h₁ : (of (fract v)⁻¹).s.get? n = none
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Tactic:
rwa [h₁, ← terminatedAt_iff_s_none,
  of_terminatedAt_n_iff_succ_nth_intFractPair_stream_eq_none, stream_succ h, ←
  of_terminatedAt_n_iff_succ_nth_intFractPair_stream_eq_none, terminatedAt_iff_s_none]

Result:
no goals

Proof state:
case inr
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

Tactic:
rcases eq_or_ne ((of (fract v)⁻¹).s.get? n) none with h₁ | h₁

Result:
case inr.inl
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
h₁ : (of (fract v)⁻¹).s.get? n = none
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n

case inr.inr
K : Type u_1
inst✝¹ : LinearOrderedField K
inst✝ : FloorRing K
v : K
n : ℕ
h : fract v ≠ 0
h₁ : (of (fract v)⁻¹).s.get? n ≠ none
⊢ (of v).s.get? (n + 1) = (of (fract v)⁻¹).s.get? n