Theorem: Matroid.Flat.exists_left_covBy_of_ssubset (Matroid/Flat.lean)

State before:
α : Type u_1
M : Matroid α
I F X Y F' F₀ F₁ F₂ P L H H₁ H₂ H' B C K : Set α
e f : α
hF₀ : M.Flat F₀
hF₁ : M.Flat F₁
hss : F₀ ⊂ F₁
⊢ ∃ F, (F₀ ⋖[M] F) ∧ F ⊆ F₁
Tactic:
obtain ⟨e, he⟩ := exists_of_ssubset hss
State after:
case intro
α : Type u_1
M : Matroid α
I F X Y F' F₀ F₁ F₂ P L H H₁ H₂ H' B C K : Set α
e✝ f : α
hF₀ : M.Flat F₀
hF₁ : M.Flat F₁
hss : F₀ ⊂ F₁
e : α
he : e ∈ F₁ ∧ e ∉ F₀
⊢ ∃ F, (F₀ ⋖[M] F) ∧ F ⊆ F₁

State before:
case intro
α : Type u_1
M : Matroid α
I F X Y F' F₀ F₁ F₂ P L H H₁ H₂ H' B C K : Set α
e✝ f : α
hF₀ : M.Flat F₀
hF₁ : M.Flat F₁
hss : F₀ ⊂ F₁
e : α
he : e ∈ F₁ ∧ e ∉ F₀
⊢ ∃ F, (F₀ ⋖[M] F) ∧ F ⊆ F₁
Tactic:
exact ⟨_, hF₀.covBy_cl_insert he.2 (hF₁.subset_ground he.1),
  hF₁.cl_subset_of_subset <| insert_subset he.1 hss.subset⟩
State after:
no goals