have hIeE := hI.diff_singleton_indep.subset_ground
α : Type u_1
M : Matroid α
I J B F₀ F F' X Y : Set α
e f : α
U✝ U : M.ModularCut
he : M.cl (M.E \ {e}) = M.E
hI : U.ExtIndep e I
hInmax : I ∉ maximals (fun x x_1 => x ⊆ x_1) {I | U.ExtIndep e I}
hBmax : B ∈ maximals (fun x x_1 => x ⊆ x_1) {I | U.ExtIndep e I}
hcon : ∀ x ∈ B \ I, ¬U.ExtIndep e (insert x I)
hB : U.ExtIndep e B
⊢ False
α : Type u_1
M : Matroid α
I J B F₀ F F' X Y : Set α
e f : α
U✝ U : M.ModularCut
he : M.cl (M.E \ {e}) = M.E
hI : U.ExtIndep e I
hInmax : I ∉ maximals (fun x x_1 => x ⊆ x_1) {I | U.ExtIndep e I}
hBmax : B ∈ maximals (fun x x_1 => x ⊆ x_1) {I | U.ExtIndep e I}
hcon : ∀ x ∈ B \ I, ¬U.ExtIndep e (insert x I)
hB : U.ExtIndep e B
hIeE : I \ {e} ⊆ M.E
⊢ False