# Thread: Logic - if and only iff

1. ## Logic - if and only iff

Hi, could anyone tell me how I would write this sentence
in first order logic:

"Bob likes to chase any animal if and only if Tom doesn't like
to chase that animal."

Bob and Tom are constants. Use the predicate L(x,y) for
"x likes to chase y".

Any help appreciated,

sabatier

2. b <--> !t

4. On the universe of animals: $\left( {\forall x} \right)\left[ {L(B,x) \Leftrightarrow \neg L(T,x)} \right]$ .