Theorem: Matroid.erk_emptyOn (Matroid/Rank.lean)

State before:
α✝ : Type u_1
ι : Type u_2
M N : Matroid α✝
I B X X' Y Y' Z R : Set α✝
n : ℕ∞
e f : α✝
α : Type u_3
⊢ (emptyOn α).erk = 0
Tactic:
simp [← (show (emptyOn α).Base ∅ by simp).encard]
State after:
no goals

State before:
α✝ : Type u_1
ι : Type u_2
M N : Matroid α✝
I B X X' Y Y' Z R : Set α✝
n : ℕ∞
e f : α✝
α : Type u_3
⊢ (emptyOn α).Base ∅
Tactic:
simp
State after:
no goals