Theorem: mul_nonneg_iff_pos_imp_nonneg
File: Mathlib/Algebra/Order/Ring/Unbundled/Basic.lean

Proof steps:
state_before: α : Type u
β : Type u_1
inst✝⁶ : Semiring α
inst✝⁵ : LinearOrder α
a b c d : α
inst✝⁴ : ExistsAddOfLE α
inst✝³ : PosMulStrictMono α
inst✝² : MulPosStrictMono α
inst✝¹ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
inst✝ : ContravariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
⊢ 0 ≤ a * b ↔ (0 < a → 0 ≤ b) ∧ (0 < b → 0 ≤ a)
state_after: α : Type u
β : Type u_1
inst✝⁶ : Semiring α
inst✝⁵ : LinearOrder α
a b c d : α
inst✝⁴ : ExistsAddOfLE α
inst✝³ : PosMulStrictMono α
inst✝² : MulPosStrictMono α
inst✝¹ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
inst✝ : ContravariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
⊢ 0 ≤ a ∧ 0 ≤ b ∨ a ≤ 0 ∧ b ≤ 0 ↔ (0 < a → 0 ≤ b) ∧ (0 < b → 0 ≤ a)
tactic: refine mul_nonneg_iff.trans ?_
state_before: α : Type u
β : Type u_1
inst✝⁶ : Semiring α
inst✝⁵ : LinearOrder α
a b c d : α
inst✝⁴ : ExistsAddOfLE α
inst✝³ : PosMulStrictMono α
inst✝² : MulPosStrictMono α
inst✝¹ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
inst✝ : ContravariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
⊢ 0 ≤ a ∧ 0 ≤ b ∨ a ≤ 0 ∧ b ≤ 0 ↔ (0 < a → 0 ≤ b) ∧ (0 < b → 0 ≤ a)
state_after: α : Type u
β : Type u_1
inst✝⁶ : Semiring α
inst✝⁵ : LinearOrder α
a b c d : α
inst✝⁴ : ExistsAddOfLE α
inst✝³ : PosMulStrictMono α
inst✝² : MulPosStrictMono α
inst✝¹ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
inst✝ : ContravariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
⊢ 0 ≤ a ∧ 0 ≤ b ∨ a ≤ 0 ∧ b ≤ 0 ↔ (a ≤ 0 ∨ 0 ≤ b) ∧ (b ≤ 0 ∨ 0 ≤ a)
tactic: simp_rw [← not_le, ← or_iff_not_imp_left]
state_before: α : Type u
β : Type u_1
inst✝⁶ : Semiring α
inst✝⁵ : LinearOrder α
a b c d : α
inst✝⁴ : ExistsAddOfLE α
inst✝³ : PosMulStrictMono α
inst✝² : MulPosStrictMono α
inst✝¹ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
inst✝ : ContravariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
⊢ 0 ≤ a ∧ 0 ≤ b ∨ a ≤ 0 ∧ b ≤ 0 ↔ (a ≤ 0 ∨ 0 ≤ b) ∧ (b ≤ 0 ∨ 0 ≤ a)
state_after: α : Type u
β : Type u_1
inst✝⁶ : Semiring α
inst✝⁵ : LinearOrder α
a b c d : α
inst✝⁴ : ExistsAddOfLE α
inst✝³ : PosMulStrictMono α
inst✝² : MulPosStrictMono α
inst✝¹ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
inst✝ : ContravariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
this : a ≤ 0 ∨ 0 ≤ a
⊢ 0 ≤ a ∧ 0 ≤ b ∨ a ≤ 0 ∧ b ≤ 0 ↔ (a ≤ 0 ∨ 0 ≤ b) ∧ (b ≤ 0 ∨ 0 ≤ a)
tactic: have := le_total a 0
state_before: α : Type u
β : Type u_1
inst✝⁶ : Semiring α
inst✝⁵ : LinearOrder α
a b c d : α
inst✝⁴ : ExistsAddOfLE α
inst✝³ : PosMulStrictMono α
inst✝² : MulPosStrictMono α
inst✝¹ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
inst✝ : ContravariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
this : a ≤ 0 ∨ 0 ≤ a
⊢ 0 ≤ a ∧ 0 ≤ b ∨ a ≤ 0 ∧ b ≤ 0 ↔ (a ≤ 0 ∨ 0 ≤ b) ∧ (b ≤ 0 ∨ 0 ≤ a)
state_after: α : Type u
β : Type u_1
inst✝⁶ : Semiring α
inst✝⁵ : LinearOrder α
a b c d : α
inst✝⁴ : ExistsAddOfLE α
inst✝³ : PosMulStrictMono α
inst✝² : MulPosStrictMono α
inst✝¹ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
inst✝ : ContravariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
this✝ : a ≤ 0 ∨ 0 ≤ a
this : b ≤ 0 ∨ 0 ≤ b
⊢ 0 ≤ a ∧ 0 ≤ b ∨ a ≤ 0 ∧ b ≤ 0 ↔ (a ≤ 0 ∨ 0 ≤ b) ∧ (b ≤ 0 ∨ 0 ≤ a)
tactic: have := le_total b 0
state_before: α : Type u
β : Type u_1
inst✝⁶ : Semiring α
inst✝⁵ : LinearOrder α
a b c d : α
inst✝⁴ : ExistsAddOfLE α
inst✝³ : PosMulStrictMono α
inst✝² : MulPosStrictMono α
inst✝¹ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
inst✝ : ContravariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
this✝ : a ≤ 0 ∨ 0 ≤ a
this : b ≤ 0 ∨ 0 ≤ b
⊢ 0 ≤ a ∧ 0 ≤ b ∨ a ≤ 0 ∧ b ≤ 0 ↔ (a ≤ 0 ∨ 0 ≤ b) ∧ (b ≤ 0 ∨ 0 ≤ a)
state_after: no goals
tactic: tauto