exact fun K ⟨hK1, hK2⟩ B hB ↦ by rw [inter_comm]; exact hK1 hK2 B hB hB.subset_ground
α : Type u_1
M : Matroid α
C C' I X C₁ C₂ R : Set α
e f x y : α
B : Set α
⊢ {X | (X ⊆ M.E → ∀ (x : Set α), M.Base x → x ⊆ M.E → (x ∩ X).Nonempty) ∧ X ⊆ M.E} ⊆
    {X | ∀ (B : Set α), M.Base B → (X ∩ B).Nonempty}
no goals