Logic is not easy but it is fun.
~E & F -- true
Either logic is easy or it will not be fun.
E v ~F -- false
If logic is easy then it will be interesting.
E -> I -- true
If logic is fun then it will be easy and interesting.
F -> (E & I) -- false
Logic will not be fun unless it is both interesting
and easy.
~F v (I & E) -- false
If it is false that logic is fun only if it
is easy, then it must be interesting.
~(F -> E) -> I -- true
Logic is both easy and fun if and only if it
is interesting.
(E & F) <-> I -- false