rw [skew_comm, skew_iff_cl_skew_left, skew_comm]
ι : Type u_1
α : Type u_2
M : Matroid α
B I J X X' Y Y' F : Set α
Xs Ys Js Is : ι → Set α
i j : ι
e f : α
hY : autoParam (Y ⊆ M.E) _auto✝
⊢ M.Skew X Y ↔ M.Skew X (M.cl Y)
no goals