exact union_subset_union_right _ <| (M.subset_cl _).trans (M.cl_inter_ground _).subset
α : Type u_1
M : Matroid α
I F X Y F' F₀ F₁ F₂ P L H H₁ H₂ H' B C K : Set α
e f : α
hF : M.cl (F ∪ M.cl C) = F ∪ C ∩ M.E
⊢ F ∪ C ∩ M.E ⊆ F ∪ M.cl C
no goals