rw [coindep_def, contract_dual_eq_dual_delete, delete_indep_iff, ← coindep_def]
α : Type u_1
M M' N : Matroid α
e f : α
I J R B X Y Z K C C₁ C₂ : Set α
⊢ (M ／ C).Coindep X ↔ M.Coindep X ∧ Disjoint X C
no goals