Theorem: Matroid.comap_emptyOn (Matroid/Map.lean)

State before:
α : Type u_1
β : Type u_2
f✝ : α → β
E I s : Set α
M : Matroid α
N : Matroid β
f : α → β
⊢ (emptyOn β).comap f = emptyOn α
Tactic:
simp [← ground_eq_empty_iff]
State after:
no goals