PAQclass

I have released an open source classification algorithm called PAQclass: https://code.google.com/p/paqclass/. I originally created PAQclass when I was working on my master's thesis but I never got around to releasing it until now. PAQclass does classification via data compression. It uses one of the best compression programs available: PAQ8. Although it is very slow, I think PAQclass is probably close to state of the art for text categorization tasks.