exact mem_of_mem_of_subset h.symm.mem_cl (M.cl_subset_cl_of_subset_cl (by simpa))
case refine_1
α : Type u_1
M N : Matroid α
e f g : α
I X✝ P D : Set α
h : M.Parallel e f
X : Set α
h' : e ∈ M.cl X
⊢ f ∈ M.cl X
no goals