What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: For all z, z is not an artist. For all z, z is a sailor if and only if z is an artist. There is at least one z for which if z were an artist, then z is a sailor.
For all z, if z were a sailor, then z is an artist can be inferred via the universal biconditional elimination rule. For all z, if z were an artist, then z is a sailor can be inferred via the universal biconditional elimination rule. For all z, z is not a sailor can be inferred via the universal biconditional elimination rule.