Theorem: C03S06.convergesTo_unique (LeanCourse/MIL/C03_Logic/S06_Sequences_and_Convergence.lean)

State before:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
⊢ a = b
Tactic:
by_contra abne
State after:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
⊢ False

State before:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
⊢ False
Tactic:
have : |a - b| > 0 := by sorry
State after:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
⊢ False

State before:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
⊢ False
Tactic:
let ε := |a - b| / 2
State after:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
⊢ False

State before:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
⊢ False
Tactic:
have εpos : ε > 0 := by
  change |a - b| / 2 > 0
  linarith
State after:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
⊢ False

State before:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
⊢ False
Tactic:
rcases sa ε εpos with ⟨Na, hNa⟩
State after:
case intro
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
⊢ False

State before:
case intro
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
⊢ False
Tactic:
rcases sb ε εpos with ⟨Nb, hNb⟩
State after:
case intro.intro
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
⊢ False

State before:
case intro.intro
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
⊢ False
Tactic:
let N := max Na Nb
State after:
case intro.intro
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
N : ℕ := max Na Nb
⊢ False

State before:
case intro.intro
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
N : ℕ := max Na Nb
⊢ False
Tactic:
have absa : |s N - a| < ε := by sorry
State after:
case intro.intro
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
N : ℕ := max Na Nb
absa : |s N - a| < ε
⊢ False

State before:
case intro.intro
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
N : ℕ := max Na Nb
absa : |s N - a| < ε
⊢ False
Tactic:
have absb : |s N - b| < ε := by sorry
State after:
case intro.intro
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
N : ℕ := max Na Nb
absa : |s N - a| < ε
absb : |s N - b| < ε
⊢ False

State before:
case intro.intro
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
N : ℕ := max Na Nb
absa : |s N - a| < ε
absb : |s N - b| < ε
⊢ False
Tactic:
have : |a - b| < |a - b| := by sorry
State after:
case intro.intro
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this✝ : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
N : ℕ := max Na Nb
absa : |s N - a| < ε
absb : |s N - b| < ε
this : |a - b| < |a - b|
⊢ False

State before:
case intro.intro
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this✝ : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
N : ℕ := max Na Nb
absa : |s N - a| < ε
absb : |s N - b| < ε
this : |a - b| < |a - b|
⊢ False
Tactic:
exact lt_irrefl _ this
State after:
no goals

State before:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
⊢ |a - b| > 0
Tactic:
sorry
State after:
no goals

State before:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
⊢ ε > 0
Tactic:
change |a - b| / 2 > 0
State after:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
⊢ |a - b| / 2 > 0

State before:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
⊢ |a - b| / 2 > 0
Tactic:
linarith
State after:
no goals

State before:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
N : ℕ := max Na Nb
⊢ |s N - a| < ε
Tactic:
sorry
State after:
no goals

State before:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
N : ℕ := max Na Nb
absa : |s N - a| < ε
⊢ |s N - b| < ε
Tactic:
sorry
State after:
no goals

State before:
s : ℕ → ℝ
a b : ℝ
sa : ConvergesTo s a
sb : ConvergesTo s b
abne : ¬a = b
this : |a - b| > 0
ε : ℝ := |a - b| / 2
εpos : ε > 0
Na : ℕ
hNa : ∀ n ≥ Na, |s n - a| < ε
Nb : ℕ
hNb : ∀ n ≥ Nb, |s n - b| < ε
N : ℕ := max Na Nb
absa : |s N - a| < ε
absb : |s N - b| < ε
⊢ |a - b| < |a - b|
Tactic:
sorry
State after:
no goals