Simple Discrete Structures problem

[Firestrider]

OK this is the first assignment I have in this class and I can't figure out how to negate and simplify the logical structure of W <--> S (bi-conditional implication)

I got this so far:

~[(W --> S) ^ (S --> W)] by Definition
~(W --> S) v ~(S --> W) by DeMorgan's Law
~(~W v S) v ~(~S v W) by Simplification of Implication

I just don't know where to go to from here. I know the end result would make W <--> S equivalent to W (XOR) S.

 

[HallsofIvy]

Why the "~"? I would start with (W--> S)^(S-->W).

Now remember that A-->B is the same as Bv(~A).

 

[Firestrider]

Well the problem says to find the simplified negation, so I thought that meant to negate then simplify. So I negated the whole thing with ~