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: ~s_4. t <-> r_3. t -> p_7. p_7 -> s_4.
~p_7 can be inferred via the modus tollens rule. t -> r_3 can be inferred via the biconditional elimination rule. r_3 -> t can be inferred via the biconditional elimination rule.