Theorem: multiplicity.multiplicity_add_eq_min
File: Mathlib/RingTheory/Multiplicity.lean

tactic: rcases lt_trichotomy (multiplicity p a) (multiplicity p b) with (hab | hab | hab)
state_before: α : Type u_1
β : Type u_2
inst✝¹ : Ring α
inst✝ : DecidableRel fun x x_1 => x ∣ x_1
p a b : α
h : multiplicity p a ≠ multiplicity p b
⊢ multiplicity p (a + b) = min (multiplicity p a) (multiplicity p b)
state_after: case inl
α : Type u_1
β : Type u_2
inst✝¹ : Ring α
inst✝ : DecidableRel fun x x_1 => x ∣ x_1
p a b : α
h : multiplicity p a ≠ multiplicity p b
hab : multiplicity p a < multiplicity p b
⊢ multiplicity p (a + b) = min (multiplicity p a) (multiplicity p b)

case inr.inl
α : Type u_1
β : Type u_2
inst✝¹ : Ring α
inst✝ : DecidableRel fun x x_1 => x ∣ x_1
p a b : α
h : multiplicity p a ≠ multiplicity p b
hab : multiplicity p a = multiplicity p b
⊢ multiplicity p (a + b) = min (multiplicity p a) (multiplicity p b)

case inr.inr
α : Type u_1
β : Type u_2
inst✝¹ : Ring α
inst✝ : DecidableRel fun x x_1 => x ∣ x_1
p a b : α
h : multiplicity p a ≠ multiplicity p b
hab : multiplicity p b < multiplicity p a
⊢ multiplicity p (a + b) = min (multiplicity p a) (multiplicity p b)

tactic: rw [add_comm, multiplicity_add_of_gt hab, min_eq_left]
state_before: case inl
α : Type u_1
β : Type u_2
inst✝¹ : Ring α
inst✝ : DecidableRel fun x x_1 => x ∣ x_1
p a b : α
h : multiplicity p a ≠ multiplicity p b
hab : multiplicity p a < multiplicity p b
⊢ multiplicity p (a + b) = min (multiplicity p a) (multiplicity p b)
state_after: case inl
α : Type u_1
β : Type u_2
inst✝¹ : Ring α
inst✝ : DecidableRel fun x x_1 => x ∣ x_1
p a b : α
h : multiplicity p a ≠ multiplicity p b
hab : multiplicity p a < multiplicity p b
⊢ multiplicity p a ≤ multiplicity p b

tactic: exact le_of_lt hab
state_before: case inl
α : Type u_1
β : Type u_2
inst✝¹ : Ring α
inst✝ : DecidableRel fun x x_1 => x ∣ x_1
p a b : α
h : multiplicity p a ≠ multiplicity p b
hab : multiplicity p a < multiplicity p b
⊢ multiplicity p a ≤ multiplicity p b
state_after: no goals

tactic: contradiction
state_before: case inr.inl
α : Type u_1
β : Type u_2
inst✝¹ : Ring α
inst✝ : DecidableRel fun x x_1 => x ∣ x_1
p a b : α
h : multiplicity p a ≠ multiplicity p b
hab : multiplicity p a = multiplicity p b
⊢ multiplicity p (a + b) = min (multiplicity p a) (multiplicity p b)
state_after: no goals

tactic: rw [multiplicity_add_of_gt hab, min_eq_right]
state_before: case inr.inr
α : Type u_1
β : Type u_2
inst✝¹ : Ring α
inst✝ : DecidableRel fun x x_1 => x ∣ x_1
p a b : α
h : multiplicity p a ≠ multiplicity p b
hab : multiplicity p b < multiplicity p a
⊢ multiplicity p (a + b) = min (multiplicity p a) (multiplicity p b)
state_after: case inr.inr
α : Type u_1
β : Type u_2
inst✝¹ : Ring α
inst✝ : DecidableRel fun x x_1 => x ∣ x_1
p a b : α
h : multiplicity p a ≠ multiplicity p b
hab : multiplicity p b < multiplicity p a
⊢ multiplicity p b ≤ multiplicity p a

tactic: exact le_of_lt hab
state_before: case inr.inr
α : Type u_1
β : Type u_2
inst✝¹ : Ring α
inst✝ : DecidableRel fun x x_1 => x ∣ x_1
p a b : α
h : multiplicity p a ≠ multiplicity p b
hab : multiplicity p b < multiplicity p a
⊢ multiplicity p b ≤ multiplicity p a
state_after: no goals