rw [circuit_iff_dep_forall_diff_singleton_indep,
  ← not_indep_iff (fundCct_subset_ground (M.cl_subset_ground I he.1)), fundCct_eq_sInter he.1]
α : Type u_1
M : Matroid α
C C' I X K C₁ C₂ R : Set α
e f x y : α
hI : M.Indep I
he : e ∈ M.cl I \ I
⊢ M.Circuit (M.fundCct e I)
α : Type u_1
M : Matroid α
C C' I X K C₁ C₂ R : Set α
e f x y : α
hI : M.Indep I
he : e ∈ M.cl I \ I
⊢ ¬M.Indep (insert e (⋂₀ {J | J ⊆ I ∧ e ∈ M.cl J})) ∧
    ∀ e_1 ∈ insert e (⋂₀ {J | J ⊆ I ∧ e ∈ M.cl J}), M.Indep (insert e (⋂₀ {J | J ⊆ I ∧ e ∈ M.cl J}) \ {e_1})