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: t_3 <-> q_11. q_11 -> p_11. p_11 -> q_11.
q_11 <-> p_11 can be inferred via the biconditional introduction rule. p_11 <-> q_11 can be inferred via the biconditional introduction rule. t_3 -> q_11 can be inferred via the biconditional elimination rule. q_11 -> t_3 can be inferred via the biconditional elimination rule.