exact hB.basis_iUnion
case intro.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
B : Set α
hB : M.ModularBase B Xs
⊢ M.Basis ((⋃ i, Xs i) ∩ B) (⋃ i, Xs i)
no goals