Ah, I screwed it up :(. I meant to say A => B /= ~A => ~B to convey the fact that if someone says that all useless things are hobbies, then it doesn't follow th

Ah, I screwed it up :(. I meant to say A => B /= ~A => ~B to convey the fact that if someone says that all useless things are hobbies, then it doesn't follow that things that aren't useless cannot be hobbies, i.e.: that all hobbies must be useless. But as groovy2shoes and MattyDub pointed out, I did it wrongly. Thanks for the kind interpretation pilgrim689 (and indeed, I could have stated that to make the same point), but I was just wrong.