exact pairwiseDisjoint_of_encard_sum_le_encard_iUnion
  (fun i ↦ (hXs i).finite_of_basis (hIs i)) (hsum.le.trans <| M.er_le_encard _)
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✝ : Fintype ι
hXs : ∀ (i : ι), M.rFin (Xs i)
hXE : ∀ (i : ι), Xs i ⊆ M.E
Is : ι → Set α
hIs : ∀ (i : ι), M.Basis (Is i) (Xs i)
hsum : ∑ x : ι, (Is x).encard = M.er (⋃ i, Is i)
⊢ univ.Pairwise (Disjoint on fun i => Is i)
no goals