tried forever to figure out a solution to this problem. It's based on the rule of Material Implication with a negation in front of both sides. Namely the premise is ~(A>B) with the goal solution being
I know how to derive the proof if there were no negations in front, but I am utterly stumped with this one. I'm thinking you want to assume (~AvB) and try to derive a contradiction by deriving (A>B) so you can use ~I as your final step, but I have no clue how this would be done. The negation in front of the premise means it is pretty much useless to work with and I'm always left with some assumptions in the dependencies if I do argue to the goal.
Let me know what any of you guys think of this. Also we are not allowed to use any sequent or theorem introductions like Rule of Implication, DeMorgan's, Law of Excluded Middle, etc. Only the basic operators like assumptions, introduction and elimination of ~,>,<>,v,&, double negation, and stuff like that.