rw [← relRank_inter_ground_right, ← relRank_inter_ground_left, relRank_eq_zero_iff,
  cl_inter_ground]
α : Type u_1
M N : Matroid α
I J C D X Y Z : Set α
e f : α
⊢ M.relRank X Y = 0 ↔ Y ∩ M.E ⊆ M.cl X
no goals