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_4. t_2 or ~s_4. t_2 <-> p.
s_4 -> t_2 can be inferred via the rewriting rule. p -> s_4 can be inferred via the biconditional elimination rule. t_2 -> p can be inferred via the biconditional elimination rule. s_4 -> p can be inferred via the biconditional elimination rule. p -> t_2 can be inferred via the biconditional elimination rule.