Proof By "Go Take Another Math Class For The Proof"

You know that feeling when your linear algebra textbook is almost done proving something, and then suddenly drops "It can be shown, by the properties of permutations discussed in an abstract algebra course,*" with a little asterisk like it's no big deal? That's basically the mathematical equivalent of "trust me bro" but with extra steps and a reading list.

The textbook is literally saying "yeah we COULD prove this determinant property right here, but nah—go take an entirely different upper-level math course first." It's the academic version of gatekeeping, except instead of a bouncer at a club, it's your textbook casually suggesting you need another semester of coursework to understand one sentence. Nothing says "simplifying computation" quite like requiring knowledge from a completely different branch of mathematics!

The highlighted section is basically math's way of saying "the proof is left as an exercise for the reader" but with more passive-aggressive energy. Classic textbook move.