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: p -> s. s -> p. p <-> s.
p <-> s can be inferred via the biconditional introduction rule. s <-> p can be inferred via the biconditional introduction rule. p -> s can be inferred via the biconditional elimination rule. s -> p can be inferred via the biconditional elimination rule.