exact fun i ↦ (h.subset_cl_inter i).trans
  (M.cl_subset_cl (inter_subset_inter_left _ (subset_iUnion _ 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.ModularBase B Xs
⊢ ∀ (i : ι), Xs i ⊆ M.cl ((⋃ i, Xs i) ∩ B)
no goals