Consider the following premises. There is at least one x_13 for which x_13 is curious if and only if x_13 is an astronaut. For all x_13, x_13 is a musician if and only if x_13 is curious. For all x_13, x_13 is not a sailor. For all x_13, if x_13 were a musician, then x_13 is a sailor. Can we infer the following from them? If we can, name the inference rule being used: For all x_13, x_13 is an astronaut.
 From the fact that there is at least one x_13 for which x_13 is curious if and only if x_13 is an astronaut we can infer that there is at least one x_13 for which if x_13 were an astronaut, then x_13 is curious via existential biconditional elimination. From the fact that for all x_13, if x_13 were a musician, then x_13 is a sailor, and that for all x_13, x_13 is not a sailor we can infer that for all x_13, x_13 is not a musician via universal modus tollens. From the fact that for all x_13, x_13 is a musician if and only if x_13 is curious, and that for all x_13, x_13 is not a musician we can infer that for all x_13, x_13 is not curious via universal biconditional elimination. Finally, from the fact that there is at least one x_13 for which if x_13 were an astronaut, then x_13 is curious, and that for all x_13, x_13 is not curious we can infer that there is at least one x_13 for which x_13 is not an astronaut via existential modus tollens, which contradicts that For all x_13, x_13 is an astronaut. Therefore, the answer is no.