simp [hB h', image_image]
case intro
α : Type u_1
β : Type u_2
M : Matroid α
N : Matroid β
e : M ≂ N
B : Set ↑M.E
I : Set ↑N.E
hI : N.Indep ↑I
hB : B ⊆ ⇑e ⁻¹' I → B = ⇑e ⁻¹' I
h' : B ⊆ ⇑e ⁻¹' I
⊢ ↑(⇑e '' B) = ↑I
no goals