. exact Basis.as_filter_le h.1
case mp.a
α : Type u_1
b c : Basis α
h : b ≤' c ∧ c ≤' b
⊢ as_filter b ≤ as_filter c

case mp.a
α : Type u_1
b c : Basis α
h : b ≤' c ∧ c ≤' b
⊢ as_filter c ≤ as_filter b
case mp.a
α : Type u_1
b c : Basis α
h : b ≤' c ∧ c ≤' b
⊢ as_filter c ≤ as_filter b