Zulip Chat Archive
Stream: Is there code for X?
Topic: coheyting operations on filters
Aaron Liu (Nov 04 2025 at 00:35):
Is there anything that connects the coheyting operations on filters to some of the more familiar ones? Like for example
import Mathlib
variable {α : Type*} (f : Filter α) (s : Set α)
open Coheyting
namespace Filter
theorem boundary_le_cofinite : boundary f ≤ cofinite := by
sorry
theorem hnot_hnot : ¬¬f = 𝓟 f.ker := by
sorry
theorem hnot_def : ¬f = 𝓟 f.kerᶜ := by
sorry
theorem hnot_principal : ¬𝓟 s = 𝓟 sᶜ := by
sorry
Last updated: Dec 20 2025 at 21:32 UTC