It would rather be than , wouldn't it ?
In this case, it would denote the gcd... but I don't see why it would equal 0.
So in which context is it ?
I dont know what this question is asking me.
It uses a symbol, an upside down U, apparently meaning intersection of sets. I have yet to deal with such an integers modulo n problem:
Let a and b be integers.
Prove that either [a]n(upside down U)[b]n = 0 or [a]n=[b]n
Note that the n's are subscripted. (congruence classes of modulo n)
Well you have a definition of intersection which is.. something along the lines of belongs to both [a]_n and [b]_n, right?
So [a]_n and [b]_n are integers. If =empty set then [a]_n will not equal [b]_n. But if = n such that n is some arbitrary integer, then out of necessity, [a]_n=n, and [b]_n=n which means [a]_n=[b]_n.