Consider the following premises. For all z, if z takes a plane, then z is a server. Susan is taking a plane or Susan is not a server. Can we infer the following from them? If is not true that Susan is a server if and only if Susan is taking a plane.
 From the fact that for all z, if z takes a plane, then z is a server we can infer that if Susan takes a plane, then Susan is a server. From the fact that Susan is taking a plane or Susan is not a server we can infer that if Susan were a server, then Susan is taking a plane. Finally, from the fact that if Susan were a server, then Susan is taking a plane, and that if Susan takes a plane, then Susan is a server we can infer that Susan is a server if and only if Susan is taking a plane, which contradicts that If is not true that Susan is a server if and only if Susan is taking a plane. Therefore, the answer is no.