Consider the following premises. If William were a bartender, then Susan is a server. If Susan were a server, then William is a bartender. Susan is not a server. If Mary were a musician, then William is a bartender. Can we infer the following from them? If we can, name the inference rule being used: Mary is a musician.
 From the fact that if William were a bartender, then Susan is a server, and that if Susan were a server, then William is a bartender we can infer that William is a bartender if and only if Susan is a server via biconditional introduction. From the fact that William is a bartender if and only if Susan is a server, and that Susan is not a server we can infer that William is not a bartender via biconditional elimination. Finally, from the fact that if Mary were a musician, then William is a bartender, and that William is not a bartender we can infer that Mary is not a musician via modus tollens, which contradicts that Mary is a musician. Therefore, the answer is no.