Theorem: Matroid.r_eq_r_inter_ground (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
M : Matroid α
X : Set α
⊢ M.r X = M.r (X ∩ M.E)
Tactic:
rw [← er_toNat_eq_r, ← er_inter_ground_eq, er_toNat_eq_r]
State after:
no goals