Theorem: Matroid.Minor.dual (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 : Matroid α
h : N ≤m M
⊢ N✶ ≤m M✶
Tactic:
obtain ⟨C, D, -, -, -, rfl⟩ := h
State after:
case intro.intro.intro.intro.intro
α : Type u_1
M M' : Matroid α
e f : α
I J R B X Y Z K : Set α
M₀ M₁ M₂ : Matroid α
C D : Set α
⊢ (M ／ C ＼ D)✶ ≤m M✶

State before:
case intro.intro.intro.intro.intro
α : Type u_1
M M' : Matroid α
e f : α
I J R B X Y Z K : Set α
M₀ M₁ M₂ : Matroid α
C D : Set α
⊢ (M ／ C ＼ D)✶ ≤m M✶
Tactic:
rw [delete_dual_eq_dual_contract, contract_dual_eq_dual_delete]
State after:
case intro.intro.intro.intro.intro
α : Type u_1
M M' : Matroid α
e f : α
I J R B X Y Z K : Set α
M₀ M₁ M₂ : Matroid α
C D : Set α
⊢ M✶ ＼ C ／ D ≤m M✶

State before:
case intro.intro.intro.intro.intro
α : Type u_1
M M' : Matroid α
e f : α
I J R B X Y Z K : Set α
M₀ M₁ M₂ : Matroid α
C D : Set α
⊢ M✶ ＼ C ／ D ≤m M✶
Tactic:
apply delete_contract_minor
State after:
no goals