rwa [parallelExtend_delete_eq', deleteElem, delete_eq_self_iff, disjoint_singleton_left]
α : Type u_1
inst✝ : DecidableEq α
M M' : Matroid α
e✝ f x : α
I C : Set α
e : α
hf : f ∉ M.E
⊢ M.parallelExtend e f ＼ f = M
no goals