rw [← restrict_compl, basis_restrict_iff, subset_diff, ← and_assoc,
  and_iff_left_of_imp Basis.subset_ground]
α : Type u_1
M M' N : Matroid α
e f : α
I J R✝ B X Y Z K D D₁ D₂ R : Set α
⊢ (M ＼ D).Basis I X ↔ M.Basis I X ∧ Disjoint X D
no goals