My brain is fried by now, I'm not sure where to go with this homework problem.
Prove that in iff (See problem 15.26).
Things that might come in handy:
Here is problem 15.26:
Prove that if , then in
For notation, see here
There's a theorem, I don't know how useful it would be in this case.
Theorem: Let and be subsets of a group . Then
I will supply any other useful information upon request.
What I tried:
Like i said, my brain is fried.
I'm not sure how to apply the part, but i know that, given that that's true, i want to show that , for
Also lost for the converse.
Thanks guys and gals