On 06/02/2025 09:02 GMT Denny Vrandečić <dvrandecic@wikimedia.org> wrote:

News in Types: Kleenean

In order to get back into creating more Types, we have kicked the year off with implementing the Type proposal for Kleenean values. This is used to represent values for a three-valued logic. Unlike Boolean logic, which has two values (True and False), the Kleenean logic has three values: True, False, and Maybe.

I do find this interesting, from the rather arcane-seeming angle of implication for the Kleenean values (aka lifted Booleans). There appear to be two different versions of "maybe" implication. Back in 2017, as a Wikimedian in Residence, I wrote a blogpost attempting to explain one of those in operational terms:

https://moore.libraries.cam.ac.uk/meet-your-wikimedian-residence/unknown

Charles