What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If it snows, then Richard is playing tennis. It is snowing or Richard is not playing tennis. If Richard plays tennis, then it is snowing.
If Richard plays tennis, then it is snowing. It is snowing if and only if Richard is playing tennis. Richard is playing tennis if and only if it is snowing.