Theorem: toZ_iterate_succ_of_not_isMax
File: Mathlib/Order/SuccPred/LinearLocallyFinite.lean

tactic: let m := (toZ i0 (succ^[n] i0)).toNat
state_before: ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
⊢ toZ i0 (succ^[n] i0) = ↑n
state_after: ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
⊢ toZ i0 (succ^[n] i0) = ↑n

tactic: have h_eq : succ^[m] i0 = succ^[n] i0 := iterate_succ_toZ _ (le_succ_iterate _ _)
state_before: ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
⊢ toZ i0 (succ^[n] i0) = ↑n
state_after: ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
h_eq : succ^[m] i0 = succ^[n] i0
⊢ toZ i0 (succ^[n] i0) = ↑n

tactic: by_cases hmn : m = n
state_before: ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
h_eq : succ^[m] i0 = succ^[n] i0
⊢ toZ i0 (succ^[n] i0) = ↑n
state_after: case pos
ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
h_eq : succ^[m] i0 = succ^[n] i0
hmn : m = n
⊢ toZ i0 (succ^[n] i0) = ↑n

case neg
ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
h_eq : succ^[m] i0 = succ^[n] i0
hmn : ¬m = n
⊢ toZ i0 (succ^[n] i0) = ↑n

tactic: suffices IsMax (succ^[n] i0) from absurd this hn
state_before: case neg
ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
h_eq : succ^[m] i0 = succ^[n] i0
hmn : ¬m = n
⊢ toZ i0 (succ^[n] i0) = ↑n
state_after: case neg
ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
h_eq : succ^[m] i0 = succ^[n] i0
hmn : ¬m = n
⊢ IsMax (succ^[n] i0)

tactic: exact isMax_iterate_succ_of_eq_of_ne h_eq.symm (Ne.symm hmn)
state_before: case neg
ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
h_eq : succ^[m] i0 = succ^[n] i0
hmn : ¬m = n
⊢ IsMax (succ^[n] i0)
state_after: no goals

tactic: nth_rw 2 [← hmn]
state_before: case pos
ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
h_eq : succ^[m] i0 = succ^[n] i0
hmn : m = n
⊢ toZ i0 (succ^[n] i0) = ↑n
state_after: case pos
ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
h_eq : succ^[m] i0 = succ^[n] i0
hmn : m = n
⊢ toZ i0 (succ^[n] i0) = ↑m

tactic: rw [Int.toNat_eq_max, toZ_of_ge (le_succ_iterate _ _), max_eq_left]
state_before: case pos
ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
h_eq : succ^[m] i0 = succ^[n] i0
hmn : m = n
⊢ toZ i0 (succ^[n] i0) = ↑m
state_after: case pos
ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
h_eq : succ^[m] i0 = succ^[n] i0
hmn : m = n
⊢ 0 ≤ ↑(Nat.find ⋯)

tactic: exact Int.natCast_nonneg _
state_before: case pos
ι : Type u_1
inst✝³ : LinearOrder ι
inst✝² : SuccOrder ι
inst✝¹ : IsSuccArchimedean ι
inst✝ : PredOrder ι
i0 i : ι
n : ℕ
hn : ¬IsMax (succ^[n] i0)
m : ℕ := (toZ i0 (succ^[n] i0)).toNat
h_eq : succ^[m] i0 = succ^[n] i0
hmn : m = n
⊢ 0 ≤ ↑(Nat.find ⋯)
state_after: no goals