Theorem: Matroid.Base.er (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
hB : M.Base B
⊢ M.er B = M.erk
Tactic:
rw [hB.indep.er, erk_eq_er_ground, hB.basis_ground.encard]
State after:
no goals