Theorem: Matroid.delete_contract_delete' (Matroid/Minor/Basic.lean)

State before:
α : Type u_1
M✝ M' N : Matroid α
e f : α
I J R B X Y Z K : Set α
M₀ M₁ M₂ M : Matroid α
D C D' : Set α
⊢ M ＼ D ／ C ＼ D' = M ／ (C \ D) ＼ (D ∪ D')
Tactic:
rw [delete_contract_comm', delete_delete]
State after:
no goals