Theorem: Matroid.delete_minor (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 : Set α
⊢ M ＼ D ≤m M
Tactic:
nth_rw 1 [← M.contract_empty]
State after:
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 : Set α
⊢ M ／ ∅ ＼ D ≤m M

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 : Set α
⊢ M ／ ∅ ＼ D ≤m M
Tactic:
apply contract_delete_minor
State after:
no goals