obtain ⟨B, hBb, hB⟩ := 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
R : Set α
h : (M ↾ R).ModularFamily Xs
⊢ M.ModularFamily fun i => Xs i ∩ M.E
case intro.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
R B : Set α
hBb : (M ↾ R).Base B
hB : ∀ (i : ι), (M ↾ R).Basis (Xs i ∩ B) (Xs i)
⊢ M.ModularFamily fun i => Xs i ∩ M.E