Factorial simplification

I converted my equation into using the product operator, but I'm not sure how to manipulate the product operator ;p

http://upload.wikimedia.org/math/c/f/d/cfd30bb9c081eb5ec7a9f252e47c729a.png

The two lower ones can be combined like this:

Prod^{xy}_{k=1} [K]
-------------------
Prod^{y}_{j=1} [Prod^{y(x-1)+1}_{k=1} [K]]

But I don't know any more ...

>>2

Fuck, sorry. Getting confused with the sigma notation. That post is wrong.