exact fun h'e ↦ he.2 (diff_subset.trans (sInter_subset_of_mem hI') h'e)
case refine'_2.inr
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
hu : M.Indep (⋃₀ {J | J ⊆ I ∧ e ∈ M.cl J})
hI' : I ∈ {J | J ⊆ I ∧ e ∈ M.cl J}
f : α
hf : ∀ t ∈ {J | J ⊆ I ∧ e ∈ M.cl J}, f ∈ t
hne : ¬e = f
hi : M.Indep (⋂₀ {J | J ⊆ I ∧ e ∈ M.cl J} \ {f})
⊢ e ∉ ⋂₀ {J | J ⊆ I ∧ e ∈ M.cl J} \ {f}
no goals