I doubt this, because for example in this interview with Arthur Whitney from 2009, his languages are named "K" and "Q": https://spawn-queue.acm.org/doi/pdf/10.

I doubt this, because for example in this interview with Arthur Whitney from 2009, his languages are named "K" and "Q": https://spawn-queue.acm.org/doi/pdf/10.1145/1515964.1531242 https://spawn-queue.acm.org/doi/pdf/10.1145/1515964.1531242 The same in this article from 2004: https://web.archive.org/web/20070101213150/http://vector.org.uk/weblog/archive/000036.html https://web.archive.org/web/20070101213150/http://vector.org... The present site of KX has some mentions about a "q", so perhaps they have changed the spelling at some point, but at least many years ago I remember seeing only "K" and "Q". Perhaps "k" and "q" refer to the interpreters of the languages, not to the languages themselves. EDIT: TFA has links to a reference manual and a user manual from 1998, which use "K programming language" for the language and "K environment" for the program that includes the user interface and the K interpreter, so I have no idea who has ever used "k" for anything related to this.