convert h.skew_compl {i}
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
h : M.SkewFamily Xs
i : ι
⊢ M.Skew (Xs i) (⋃ j ∈ {i}ᶜ, Xs j)
case h.e'_3
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
h : M.SkewFamily Xs
i : ι
⊢ Xs i = ⋃ i_1 ∈ {i}, Xs i_1