rw [inter_distrib_right B (A \ B) _]
α : Type u_1
G : SimpleGraph α
inst✝² : Fintype α
inst✝¹ : DecidableEq α
inst✝ : DecidableRel G.Adj
B A : Finset α
v : α
hB : B ⊆ A
⊢ card ((B ∪ A \ B) ∩ neighborFinset G v) = card (B ∩ neighborFinset G v) + card (A \ B ∩ neighborFinset G v)
α : Type u_1
G : SimpleGraph α
inst✝² : Fintype α
inst✝¹ : DecidableEq α
inst✝ : DecidableRel G.Adj
B A : Finset α
v : α
hB : B ⊆ A
⊢ card (B ∩ neighborFinset G v ∪ A \ B ∩ neighborFinset G v) =
    card (B ∩ neighborFinset G v) + card (A \ B ∩ neighborFinset G v)