What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? It is snowing if and only if Joseph is a cashier. Joseph is not a cashier. Karen is writing a letter and Michael is a sailor.
Karen is writing a letter. Michael is a sailor. If it snows, then Joseph is a cashier. If Joseph were a cashier, then it is snowing. It is not snowing.