\lnot(First \land Second) \iff \lnot First \lor \lnot Second
  First\lor\true \implies\true
First \land \true \implies First
(First \lor \true) \land Second \implies Second
(First \land \true) \lor Second \implies First \lor Second
((First \implies Second) \land (Second \implies First)) \iff (First \iff Second)