Theorem: Matroid.Minor.subset (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.E ⊆ M.E
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).E ⊆ M.E

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).E ⊆ M.E
Tactic:
exact diff_subset.trans diff_subset
State after:
no goals