For anyone who uses ¡ (inverted exclamation mark) in a mathematical context, how do you pronounce it?
Background: I have privately been using ¡ in a couple of notations for a while, and am considering using it in a paper. One of my reservations about doing so is pronouncability: it isn’t standardly used for anything in the areas I work in, so if I use it in print, I’ll give a suggested pronunciation (incidentally, something I wish more authors would do when introducing notations for which there’s not an obvious/established reading).
The only existing usage I have found mentioned is as an old (?obsolete) notation for subfactorial. But, as an easily recognisable and available symbol, I guess it has probably been co-opted by other mathematicians on occasion.
For what it’s worth, I pronounce it to myself as “gnab”.