Rigorous proof that you're wrong
1. Define wrong:
The OP is wrong if and only if his/her username is Fat Fish Pete
2. The proof
P<--->Q == (P-->Q) ^ (Q -->P)
2.1 P-->Q
2.1.1 The OP's Username is Fat Fish Pete
2.1.2 The OP is wrong
2.2 Q-->P
2.2.1 The OP is wrong
2.2.2 The OP's username is Fat Fish Pete
Therefore, You, The OP whose username is Fat Fish Pete, are wrong.
Q.E.D.