exact fun heIs ↦ he.2 (sInter_subset_of_mem hI' heIs)
case refine'_1.heI
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}
hi : M.Indep (insert e (⋂₀ {J | J ⊆ I ∧ e ∈ M.cl J}))
⊢ e ∉ ⋂₀ {J | J ⊆ I ∧ e ∈ M.cl J}
no goals