currently I am trying to write a restriction based on a set that I have, and for some reason I have been struggling a lot.
So I have a set A= A1 $\cup$ A2 $\cup$ A3 $\cup$ A4
And the restriction I want to write is that a location lets say Y can be either A2 or A3 . (not both at the same time) How I can write that?
Thank you in advance!