Theorem: Matroid.Indep.insert_indep_iff_of_not_mem (Matroid/Closure.lean)

State before:
α : Type u_1
ι : Type u_2
M : Matroid α
F I J X Y B C R : Set α
e f x y : α
hI : M.Indep I
heI : e ∉ I
⊢ M.Indep (insert e I) ↔ e ∈ M.E \ M.cl I
Tactic:
rw [mem_diff, hI.mem_cl_iff_of_not_mem heI, dep_iff, not_and, not_imp_not, insert_subset_iff,
  and_iff_left hI.subset_ground]
State after:
α : Type u_1
ι : Type u_2
M : Matroid α
F I J X Y B C R : Set α
e f x y : α
hI : M.Indep I
heI : e ∉ I
⊢ M.Indep (insert e I) ↔ e ∈ M.E ∧ (e ∈ M.E → M.Indep (insert e I))

State before:
α : Type u_1
ι : Type u_2
M : Matroid α
F I J X Y B C R : Set α
e f x y : α
hI : M.Indep I
heI : e ∉ I
⊢ M.Indep (insert e I) ↔ e ∈ M.E ∧ (e ∈ M.E → M.Indep (insert e I))
Tactic:
exact ⟨fun h ↦ ⟨h.subset_ground (mem_insert e I), fun _ ↦ h⟩, fun h ↦ h.2 h.1⟩
State after:
no goals