simp only [deleteElem, contract_elem, contract_dual_eq_dual_delete]
α : Type u_1
inst✝ : DecidableEq α
M✝ M' : Matroid α
e✝ f✝ : α
M : Matroid α
e f : α
hef : e ≠ f
⊢ ((M✶ ＼ f).parallelExtend e f)✶ = ((M ／ f)✶.parallelExtend e f)✶
no goals