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