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: r_4 -> t. q_3 <-> r_4. ~t.
~r_4 can be inferred via the modus tollens rule. q_3 -> r_4 can be inferred via the biconditional elimination rule. r_4 -> q_3 can be inferred via the biconditional elimination rule.