The contrapositive of PrightarrowQP \\rightarrow QPrightarrowQ is:
negQrightarrownegP\\neg Q \\rightarrow \\neg PnegQrightarrownegP
negPrightarrownegQ\\neg P \\rightarrow \\neg QnegPrightarrownegQ
QrightarrowPQ \\rightarrow PQrightarrowP
QlorPQ \\lor PQlorP