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: u_2 <-> q_11. u_2 <-> q_11.
u_2 -> q_11 can be inferred via the biconditional elimination rule. u_2 -> q_11 can be inferred via the biconditional elimination rule. q_11 -> u_2 can be inferred via the biconditional elimination rule. q_11 -> u_2 can be inferred via the biconditional elimination rule.