Theorem: Matroid.restriction_iff_exists_eq_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 D D₁ D₂ R : Set α
⊢ (∃ D ⊆ M.E, N = M ＼ D) → N ≤r M
Tactic:
rintro ⟨D, -, rfl⟩
State after:
case intro.intro
α : Type u_1
M M' : Matroid α
e f : α
I J R✝ B X Y Z K D✝ D₁ D₂ R D : Set α
⊢ M ＼ D ≤r M

State before:
case intro.intro
α : Type u_1
M M' : Matroid α
e f : α
I J R✝ B X Y Z K D✝ D₁ D₂ R D : Set α
⊢ M ＼ D ≤r M
Tactic:
apply delete_restriction
State after:
no goals