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: There is at least one z_2 for which z_2 will play squash if and only if z_2 will read a book. For all z_2, z_2 is excited if and only if z_2 will play squash.
For all z_2, if z_2 were excited, then z_2 is playing squash can be inferred via the universal biconditional elimination rule. There is at least one z_2 for which if z_2 plays squash, then z_2 is reading a book can be inferred via the existential biconditional elimination rule. For all z_2, if z_2 plays squash, then z_2 is excited can be inferred via the universal biconditional elimination rule. There is at least one z_2 for which if z_2 reads a book, then z_2 is playing squash can be inferred via the existential biconditional elimination rule.