intro x hx
α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
M : MultiPart α
⊢ ∀ (x : ℕ),
    x ∈ range (M.t + 1) →
      ∑ i in MultiPart.P M x, degree (mp M) i = card (MultiPart.P M x) * card (M.A \ MultiPart.P M x)
α : Type u_1
inst✝¹ : Fintype α
inst✝ : DecidableEq α
M : MultiPart α
x : ℕ
hx : x ∈ range (M.t + 1)
⊢ ∑ i in MultiPart.P M x, degree (mp M) i = card (MultiPart.P M x) * card (M.A \ MultiPart.P M x)