Let A be a set. Prove that 2^A, delta) is a group.
Of course it is. I bet somebody else's children that he meant that the power set of any set is a group under the operation of symmetric difference.
In fact, not only is that group but it actually is an elementary abelian group of exponent 2.
But let him realize his sloppy question and re-post it in an acceptable way.
Tonio