exact hB.base.indep.subset (iUnion_subset (fun _ ↦ inter_subset_right))
case h
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
inst✝ : Nonempty ι
hB : M.ModularBase B Xs
⊢ M.Indep (⋃ i, Xs i ∩ B)
no goals