What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? It is sunny if and only if John is a writer. If John sleeps, then John is a writer. For all x_13, if x_13 were rich, then x_13 is sleeping. It is not sunny. For all x_13, if x_13 were a writer, then x_13 is rich.
If it is sunny, then John is a writer. If John were a writer, then it is sunny. John is not a writer. For all x_13, if x_13 were a writer, then x_13 is sleeping.