rw [delete_contract_diff, ← contract_delete_comm _ disjoint_sdiff_left]
α : Type u_1
M✝ M' N : Matroid α
e f : α
I J R B X Y Z K : Set α
M₀ M₁ M₂ M : Matroid α
D C : Set α
⊢ M ＼ D ／ C = M ／ (C \ D) ＼ D
no goals