What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_15, if x_15 were a police officer, then x_15 is happy. Barbara is a police officer. For all x_15, if x_15 were happy, then x_15 is a police officer. Barbara is not happy.
Since the premises are contradictory, we can infer anything from them.