Theorem: Matroid.Basis'.er_eq_er_union (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
hIX : M.Basis' I X
Y : Set α
⊢ M.er (I ∪ Y) = M.er (X ∪ Y)
Tactic:
rw [← er_union_cl_left_eq, hIX.cl_eq_cl, er_union_cl_left_eq]
State after:
no goals