I've been trying to give a formal proof for $$ \lnot \left(p \lor \lnot q\right) \rightarrow \left(\lnot p \land q \right) $$
in deductive system N (natural deduction system) and got stuck. I've started by assuming $$A1 \Rightarrow\lnot \left(p \lor \lnot q\right) $$
and tried to prove by contradiction with $$A2 \Rightarrow \left(p \lor \lnot q\right) $$ but got stuck. Am I looking at this problem from the wrong point of view? Any assistance will be appreciated.