exact h.pairwise_disjoint_of_indep_subsets
  (fun i ↦ (hIs i).subset.trans (hYX i)) (fun i ↦ (hIs i).indep)
case refine_2
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
hYX : ∀ (i : ι), Ys i ⊆ Xs i
Is : ι → Set α
hIs : ∀ (i : ι), M.Basis (Is i) (Ys i)
⊢ Pairwise (Disjoint on fun i => Is i)
no goals