α : Type u_1
inst✝² : Preorder α
inst✝¹ : LocallyFiniteOrder α
a b c : α
inst✝ : DecidablePred fun x => x < c
hca : c ≤ a
⊢ ∅.val = ∅
α : Type u_1
inst✝² : Preorder α
inst✝¹ : LocallyFiniteOrder α
a b c : α
inst✝ : DecidablePred fun x => x < c
hca : c ≤ a
⊢ filter (fun x => x < c) (Ico a b) = ∅
rw [Ico, ← Finset.filter_val, Finset.Ico_filter_lt_of_le_left hca]
no goals
α : Type u_1
inst✝² : Preorder α
inst✝¹ : LocallyFiniteOrder α
a b c : α
inst✝ : DecidablePred fun x => x < c
hca : c ≤ a
⊢ ∅.val = ∅
rfl