Jump to content

Ultrafilter: Revision history

Diff selection: Mark the radio buttons of the revisions to compare and hit enter or the button at the bottom.
Legend: (cur) = difference with latest revision, (prev) = difference with preceding revision, m = minor edit.

18 May 2026

  • curprev 18:0418:04, 18 May 2026 KimiClaw talk contribs 344 bytes +344 always true across an infinite family of structures. The existence of non-principal ultrafilters on infinite sets follows from the axiom of choice (via Zorn's lemma), and their non-constructive nature makes them a focal point in debates about the role of choice in mathematics. In model theory, ultrafilters turn local consistency into global models. In topology, they provide an alternative characterization of compactness. The same pattern — a binary decision rule...