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_1 -> q. s_1 or ~q. s_1 <-> q.
q -> s_1 can be inferred via the rewriting rule. s_1 -> q can be inferred via the biconditional elimination rule. q -> s_1 can be inferred via the biconditional elimination rule.