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: James is not taking a plane. For all z, z will take a plane if and only if z will work. Susan is an artist.
James is not taking a plane and Susan is an artist can be inferred via the conjunction rule. Susan is an artist and James is not taking a plane can be inferred via the conjunction rule. For all z, if z takes a plane, then z is working can be inferred via the universal biconditional elimination rule. For all z, if z works, then z is taking a plane can be inferred via the universal biconditional elimination rule.