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.ker := by
  sorry

theorem hnot_principal : 𝓟 s = 𝓟 s := by
  sorry

Last updated: Dec 20 2025 at 21:32 UTC