I have one of De Morgan's laws (in propositional logic). I would like to prove the other law from the first using a sequence of equivalences (Resolution).
One is not allowed to use truth tables or the particular De Morgans law which we are trying to prove (obviously).
How can this be done?
$\lnot (A\land B)\equiv \lnot A \lor \lnot B$
$\lnot (A\lor B)\equiv \lnot A \land \lnot B$