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 for which z is curious if and only if z will play squash. For all z, if z takes a plane, then z is a janitor. For all z, if z were a janitor, then z is curious. For all z, z will take a plane or z will not play squash.
For all z, if z takes a plane, then z is curious can be inferred via the universal transitivity rule. For all z, if z plays squash, then z is taking a plane can be inferred via the universal rewriting rule. There is at least one z for which if z were curious, then z is playing squash can be inferred via the existential biconditional elimination rule. There is at least one z for which if z plays squash, then z is curious can be inferred via the existential biconditional elimination rule.