How do you express that a variable = one thing OR another thing

Question

I want to write an equation where y will be either x or x^-1 depending on the circumstance, how do I show that? Like, off to the side i want to put something like y= x or x^-1, but is there an official way to do that?

Answer 1

∧ means and (from the Latin aut)

∨ means or (from the Latin vel)