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 a writer. Richard is a writer or it is not late. If Richard were a writer, then it is snowing. It is not snowing.
Richard is not a writer. If it is late, then Richard is a writer. It is snowing if and only if Richard is a writer. Richard is a writer if and only if it is snowing.