Theorem: Matroid.er_union_cl_left_eq (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 Y : Set α
⊢ M.er (M.cl X ∪ Y) = M.er (X ∪ Y)
Tactic:
rw [← er_cl_eq, cl_union_cl_left_eq, er_cl_eq]
State after:
no goals