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 were happy, then x_3 is sad. For all x_3, x_3 is not sad. For all x_3, if x_3 were sad, then x_3 is happy. There is at least one x_3 for which if x_3 were sad, then x_3 is happy.
For all x_3, x_3 is not happy. For all x_3, x_3 is happy if and only if x_3 is sad. For all x_3, x_3 is sad if and only if x_3 is happy. There is at least one x_3 for which x_3 is sad if and only if x_3 is happy. There is at least one x_3 for which x_3 is happy if and only if x_3 is sad.