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, if z_2 plays squash, then z_2 is sleeping. For all z_2, z_2 will play squash if and only if z_2 will sleep.
For all z_2, if z_2 plays squash, then z_2 is sleeping can be inferred via the universal biconditional elimination rule. For all z_2, if z_2 sleeps, then z_2 is playing squash can be inferred via the universal biconditional elimination rule.