Theorem: Mathlib.Meta.NormNum.isRat_lt_true
File: Mathlib/Tactic/NormNum/Ineq.lean

Proof steps:
state_before: u : Level
α : Type u_1
inst✝¹ : LinearOrderedRing α
inst✝ : Nontrivial α
num✝¹ num✝ : ℤ
da db : ℕ
inv✝¹ : Invertible ↑da
inv✝ : Invertible ↑db
h : decide (num✝¹ * ↑db < num✝ * ↑da) = true
⊢ ↑num✝¹ * ⅟↑da < ↑num✝ * ⅟↑db
state_after: u : Level
α : Type u_1
inst✝¹ : LinearOrderedRing α
inst✝ : Nontrivial α
num✝¹ num✝ : ℤ
da db : ℕ
inv✝¹ : Invertible ↑da
inv✝ : Invertible ↑db
h✝ : decide (num✝¹ * ↑db < num✝ * ↑da) = true
h : (fun x => ↑x) (num✝¹ * ↑db) < (fun x => ↑x) (num✝ * ↑da)
⊢ ↑num✝¹ * ⅟↑da < ↑num✝ * ⅟↑db
tactic: have h := Int.cast_strictMono (R := α) <| of_decide_eq_true h
state_before: u : Level
α : Type u_1
inst✝¹ : LinearOrderedRing α
inst✝ : Nontrivial α
num✝¹ num✝ : ℤ
da db : ℕ
inv✝¹ : Invertible ↑da
inv✝ : Invertible ↑db
h✝ : decide (num✝¹ * ↑db < num✝ * ↑da) = true
h : (fun x => ↑x) (num✝¹ * ↑db) < (fun x => ↑x) (num✝ * ↑da)
⊢ ↑num✝¹ * ⅟↑da < ↑num✝ * ⅟↑db
state_after: u : Level
α : Type u_1
inst✝¹ : LinearOrderedRing α
inst✝ : Nontrivial α
num✝¹ num✝ : ℤ
da db : ℕ
inv✝¹ : Invertible ↑da
inv✝ : Invertible ↑db
h✝ : decide (num✝¹ * ↑db < num✝ * ↑da) = true
h : (fun x => ↑x) (num✝¹ * ↑db) < (fun x => ↑x) (num✝ * ↑da)
ha : 0 < ⅟↑da
⊢ ↑num✝¹ * ⅟↑da < ↑num✝ * ⅟↑db
tactic: have ha : 0 < ⅟(da : α) := pos_invOf_of_invertible_cast da
state_before: u : Level
α : Type u_1
inst✝¹ : LinearOrderedRing α
inst✝ : Nontrivial α
num✝¹ num✝ : ℤ
da db : ℕ
inv✝¹ : Invertible ↑da
inv✝ : Invertible ↑db
h✝ : decide (num✝¹ * ↑db < num✝ * ↑da) = true
h : (fun x => ↑x) (num✝¹ * ↑db) < (fun x => ↑x) (num✝ * ↑da)
ha : 0 < ⅟↑da
⊢ ↑num✝¹ * ⅟↑da < ↑num✝ * ⅟↑db
state_after: u : Level
α : Type u_1
inst✝¹ : LinearOrderedRing α
inst✝ : Nontrivial α
num✝¹ num✝ : ℤ
da db : ℕ
inv✝¹ : Invertible ↑da
inv✝ : Invertible ↑db
h✝ : decide (num✝¹ * ↑db < num✝ * ↑da) = true
h : (fun x => ↑x) (num✝¹ * ↑db) < (fun x => ↑x) (num✝ * ↑da)
ha : 0 < ⅟↑da
hb : 0 < ⅟↑db
⊢ ↑num✝¹ * ⅟↑da < ↑num✝ * ⅟↑db
tactic: have hb : 0 < ⅟(db : α) := pos_invOf_of_invertible_cast db
state_before: u : Level
α : Type u_1
inst✝¹ : LinearOrderedRing α
inst✝ : Nontrivial α
num✝¹ num✝ : ℤ
da db : ℕ
inv✝¹ : Invertible ↑da
inv✝ : Invertible ↑db
h✝¹ : decide (num✝¹ * ↑db < num✝ * ↑da) = true
h✝ : (fun x => ↑x) (num✝¹ * ↑db) < (fun x => ↑x) (num✝ * ↑da)
ha : 0 < ⅟↑da
hb : 0 < ⅟↑db
h : ⅟↑db * ((fun x => ↑x) (num✝¹ * ↑db) * ⅟↑da) < ⅟↑db * ((fun x => ↑x) (num✝ * ↑da) * ⅟↑da)
⊢ ↑num✝¹ * ⅟↑da < ↑num✝ * ⅟↑db
state_after: u : Level
α : Type u_1
inst✝¹ : LinearOrderedRing α
inst✝ : Nontrivial α
num✝¹ num✝ : ℤ
da db : ℕ
inv✝¹ : Invertible ↑da
inv✝ : Invertible ↑db
h✝¹ : decide (num✝¹ * ↑db < num✝ * ↑da) = true
h✝ : (fun x => ↑x) (num✝¹ * ↑db) < (fun x => ↑x) (num✝ * ↑da)
ha : 0 < ⅟↑da
hb : 0 < ⅟↑db
h : ↑(num✝¹ * ↑db) * ⅟↑db * ⅟↑da < ⅟↑db * ((fun x => ↑x) (num✝ * ↑da) * ⅟↑da)
⊢ ↑num✝¹ * ⅟↑da < ↑num✝ * ⅟↑db
tactic: rw [← mul_assoc, Int.commute_cast] at h
state_before: u : Level
α : Type u_1
inst✝¹ : LinearOrderedRing α
inst✝ : Nontrivial α
num✝¹ num✝ : ℤ
da db : ℕ
inv✝¹ : Invertible ↑da
inv✝ : Invertible ↑db
h✝¹ : decide (num✝¹ * ↑db < num✝ * ↑da) = true
h✝ : (fun x => ↑x) (num✝¹ * ↑db) < (fun x => ↑x) (num✝ * ↑da)
ha : 0 < ⅟↑da
hb : 0 < ⅟↑db
h : ↑(num✝¹ * ↑db) * ⅟↑db * ⅟↑da < ⅟↑db * ((fun x => ↑x) (num✝ * ↑da) * ⅟↑da)
⊢ ↑num✝¹ * ⅟↑da < ↑num✝ * ⅟↑db
state_after: u : Level
α : Type u_1
inst✝¹ : LinearOrderedRing α
inst✝ : Nontrivial α
num✝¹ num✝ : ℤ
da db : ℕ
inv✝¹ : Invertible ↑da
inv✝ : Invertible ↑db
h✝¹ : decide (num✝¹ * ↑db < num✝ * ↑da) = true
h✝ : (fun x => ↑x) (num✝¹ * ↑db) < (fun x => ↑x) (num✝ * ↑da)
ha : 0 < ⅟↑da
hb : 0 < ⅟↑db
h : ↑num✝¹ * ⅟↑da < ⅟↑db * ↑num✝
⊢ ↑num✝¹ * ⅟↑da < ↑num✝ * ⅟↑db
tactic: simp? at h says simp only [Int.cast_mul, Int.cast_natCast, mul_mul_invOf_self_cancel'] at h
state_before: u : Level
α : Type u_1
inst✝¹ : LinearOrderedRing α
inst✝ : Nontrivial α
num✝¹ num✝ : ℤ
da db : ℕ
inv✝¹ : Invertible ↑da
inv✝ : Invertible ↑db
h✝¹ : decide (num✝¹ * ↑db < num✝ * ↑da) = true
h✝ : (fun x => ↑x) (num✝¹ * ↑db) < (fun x => ↑x) (num✝ * ↑da)
ha : 0 < ⅟↑da
hb : 0 < ⅟↑db
h : ↑num✝¹ * ⅟↑da < ⅟↑db * ↑num✝
⊢ ↑num✝¹ * ⅟↑da < ↑num✝ * ⅟↑db
state_after: no goals
tactic: rwa [Int.commute_cast] at h