rw [← indep_singleton, restrict_indep_iff, singleton_subset_iff, indep_singleton]
α : Type u_1
β : Type u_2
M N : Matroid α
e f : α
B L L' I X Y Z F C K R : Set α
⊢ (M ↾ R).Nonloop e ↔ M.Nonloop e ∧ e ∈ R
no goals