Consider the following premises. For all z, z is a server or z will not play squash. For all z, z is not a server. For all z, if z were a server, then z is playing squash. Can we infer the following from them? If we can, name the inference rule being used: There is at least one z for which z will play squash.
 From the fact that for all z, z is a server or z will not play squash we can infer that for all z, if z plays squash, then z is a server via universal rewriting. From the fact that for all z, if z were a server, then z is playing squash, and that for all z, if z plays squash, then z is a server we can infer that for all z, z is a server if and only if z will play squash via universal biconditional introduction. Finally, from the fact that for all z, z is a server if and only if z will play squash, and that for all z, z is not a server we can infer that for all z, z will not play squash via universal biconditional elimination, which contradicts that There is at least one z for which z will play squash. Therefore, the answer is no.