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