Consider the following premises. For all x_6, x_6 is not happy or x_6 is a cashier. For all x_6, x_6 is a musician if and only if x_6 is a janitor. There is at least one x_6 for which x_6 is happy or x_6 is a janitor. For all x_6, if x_6 were a cashier, then x_6 is a musician. Can we infer the following from them? If we can, name the inference rule being used: For all x_6, x_6 is not a musician.
 From the fact that there is at least one x_6 for which x_6 is happy or x_6 is a janitor, and that for all x_6, x_6 is not happy or x_6 is a cashier we can infer that there is at least one x_6 for which x_6 is a janitor or x_6 is a cashier via existential resolution. From the fact that for all x_6, x_6 is a musician if and only if x_6 is a janitor we can infer that for all x_6, if x_6 were a janitor, then x_6 is a musician via universal biconditional elimination. Finally, from the fact that for all x_6, if x_6 were a janitor, then x_6 is a musician, that for all x_6, if x_6 were a cashier, then x_6 is a musician, and that there is at least one x_6 for which x_6 is a janitor or x_6 is a cashier we can infer that there is at least one x_6 for which x_6 is a musician via existential disjunction elimination, which contradicts that For all x_6, x_6 is not a musician. Therefore, the answer is no.