I'm stuck on how to progress with this proof, despite I have tried, I cannot see the next move.
Given this proof without predicate:
So far what I've accomplished:
My idea is, as I can't see any other option using
(-(Sv(P->Q)) as the first assumption in order to introduce a conditional, so the assumption must end in
P ^ -Q ^ -S. As you can see I have obatined
-Q and -S but, how do I proof