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: If John sleeps, then Jennifer is playing squash. If Jennifer plays tennis, then John is sleeping. If Jennifer plays tennis, then Jennifer is playing squash. If Jennifer plays squash, then Jennifer is playing tennis.
If John sleeps, then Jennifer is playing tennis can be inferred via the transitivity rule. If Jennifer plays tennis, then Jennifer is playing squash can be inferred via the transitivity rule. If Jennifer plays squash, then John is sleeping can be inferred via the transitivity rule. Jennifer is playing tennis if and only if Jennifer is playing squash can be inferred via the biconditional introduction rule. Jennifer is playing squash if and only if Jennifer is playing tennis can be inferred via the biconditional introduction rule.