According to De Morgan's Laws, neg(PlorQ)\\neg(P \\lor Q)neg(PlorQ) is equivalent to:
negPlandnegQ\\neg P \\land \\neg QnegPlandnegQ
negPlornegQ\\neg P \\lor \\neg QnegPlornegQ
PlandQP \\land QPlandQ
negPrightarrowQ\\neg P \\rightarrow QnegPrightarrowQ