rw [eq_loopyOn_iff_cl, contract_ground, and_iff_left rfl, contract_cl_eq, empty_union, h.cl_eq]
α : Type u_1
M M' N : Matroid α
e f : α
I J R B X Y Z K E C : Set α
h : M.Spanning C
⊢ M ／ C = loopyOn (M.E \ C)
no goals