What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Mary takes a plane, then it is cloudy. Mary is not taking a plane. It is cloudy or John is a bartender. If it is cloudy, then Mary is taking a plane.
It is not cloudy. Mary is taking a plane if and only if it is cloudy. It is cloudy if and only if Mary is taking a plane.