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_2, z_2 will play tennis if and only if z_2 is a poet. There is at least one z_2 for which if z_2 were a poet, then z_2 is playing tennis.
For all z_2, if z_2 plays tennis, then z_2 is a poet can be inferred via the universal biconditional elimination rule. For all z_2, if z_2 were a poet, then z_2 is playing tennis can be inferred via the universal biconditional elimination rule.