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 a sailor if and only if z will read a book. For all z, z will read a book if and only if z is a sailor.
For all z, if z were a sailor, then z is reading a book can be inferred via the universal biconditional elimination rule. For all z, if z reads a book, then z is a sailor can be inferred via the universal biconditional elimination rule. For all z, if z reads a book, then z is a sailor can be inferred via the universal biconditional elimination rule. For all z, if z were a sailor, then z is reading a book can be inferred via the universal biconditional elimination rule.