exact iff_of_true (mem_cl_of_mem _ hxI hI.indep.subset_ground)
  (mem_cl_of_mem' _ (mem_image_of_mem f (hI.subset hxI))
    (hI'.indep.subset_ground (mem_image_of_mem f hxI)))
case intro.intro.intro.h.inr.inl
α : Type u_1
ι : Type u_2
M✝ : Matroid α
F I✝ J X✝ Y B C R : Set α
e f✝ x✝ y : α
β : Type u_3
M : Matroid β
f : α → β
X I : Set α
hI : (M.comap f).Basis' I X
hI' : M.Basis' (f '' I) (f '' X)
hIinj : InjOn f I
x : α
hxE : f x ∈ M.E
hxI : x ∈ I
⊢ x ∈ (M.comap f).cl I ↔ x ∈ f ⁻¹' M.cl (f '' X)
no goals