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: q <-> r_3. r_3 <-> s_3. q -> s_3.
q -> r_3 can be inferred via the biconditional elimination rule. r_3 -> s_3 can be inferred via the biconditional elimination rule. r_3 -> q can be inferred via the biconditional elimination rule. s_3 -> r_3 can be inferred via the biconditional elimination rule.