rcases ‹Nonempty α› with ⟨a⟩
case inl
α : Type u
β : Type v
inst✝² : BishopFin α
inst✝¹ : BishopFin β
inst✝ : Nonempty α
h0 : List.length (elems α) = 0
⊢ card α ≥ 1
case inl.intro
α : Type u
β : Type v
inst✝² : BishopFin α
inst✝¹ : BishopFin β
inst✝ : Nonempty α
h0 : List.length (elems α) = 0
a : α
⊢ card α ≥ 1