What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_3, if x_3 sleeps, then x_3 is sad. For all x_3, x_3 is not an astronaut. For all x_3, x_3 is an astronaut if and only if x_3 is sad.
For all x_3, if x_3 were an astronaut, then x_3 is sad. For all x_3, if x_3 were sad, then x_3 is an astronaut. For all x_3, x_3 is not sad.