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 <-> q_12. q_12 or q_4. p_1 <-> p. ~p_1.
p -> q_12 can be inferred via the biconditional elimination rule. p_1 -> p can be inferred via the biconditional elimination rule. q_12 -> p can be inferred via the biconditional elimination rule. p -> p_1 can be inferred via the biconditional elimination rule. ~p can be inferred via the biconditional elimination rule.