Binary symmetric channel capacity

[dervast]

Hi to our nice community. I want to learn why
in a binary symetric channel the channel is calculated as
C=1+plogp+(1-p)log(1-p)

I only know that the channel is denoted as C=maxI(X;Y)
btw what ; means in X;Y?
Unfortunately my book doesn't mention these things so if u can reply me or provide me with some good links that will be rezlly nicenow i need something more
Why in a binary symetric channel the channel is calculated for
C=1+plogp+(1-p)log(1-p)

I only know that the channel is denoted as C=maxI(X;Y)
btw what ; means in X;Y?
Unfortunately my book doesn't mention these things so if u can reply me or provide me with some good links that will be rezlly nice

 

[Drakkith]

Replying so that this thread isn't a no-reply, as per Greg's wishes.
If anyone has knowledge on this subject, feel free to reply.