dsimp [count]
α : Type u
β : Type v
inst✝³ : BishopFin α
inst✝² : BishopFin β
p q : α → Prop
inst✝¹ : DecidablePred p
inst✝ : DecidablePred q
h : ∀ (a : α), ¬(p a ∧ q a)
⊢ (count fun a => p a ∨ q a) = count p + count q
α : Type u
β : Type v
inst✝³ : BishopFin α
inst✝² : BishopFin β
p q : α → Prop
inst✝¹ : DecidablePred p
inst✝ : DecidablePred q
h : ∀ (a : α), ¬(p a ∧ q a)
⊢ List.countP (fun a => decide (p a ∨ q a)) (elems α) =
    List.countP (fun a => decide (p a)) (elems α) + List.countP (fun a => decide (q a)) (elems α)