rw [← indep_singleton, delete_indep_iff, disjoint_singleton_left, indep_singleton]
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).Nonloop e ↔ M.Nonloop e ∧ e ∉ D
no goals