exact (hI.nonloop_of_mem heI).not_loop <| h.loop_of_mem_inter hij ⟨hei,hej⟩
case intro
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
hI : M.Indep I
hij : i ≠ j
e : α
hei : e ∈ Xs i
heI : e ∈ I
hej : e ∈ Xs j
⊢ False
no goals