exact modularPair_of_subset (M.cl_subset_cl (subset_insert _ _)) (M.cl_subset_ground _)
case intro.inr.inl
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
M : Matroid α
X : Set α
e f : α
I : Set α
hI : M.Basis' I X
he : e ∈ M.E
hf : f ∉ M.E
⊢ M.ModularPair (M.cl (M.cl I)) (M.cl (insert e (M.cl I)))
no goals