CQK Is The First Unused TLA
<p>Curious what the first ‘unused’ alphabetic acronym is, I have GPT-4 write a script to check English Wikipedia. After three bugs, the first unused one turns out as of 2023-09-29 to be the three-letter acronym ‘CQK’, with another 2.6k TLA unused, and 393k four-letter acronyms unused. Exploratory analysis suggests alphabetical order effects as well as letter-frequency.</p>
Source: gwern.net