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. ~q_10 -> u. p_15 <-> t. q_10 -> p_15. p_15 -> q_10.
q_10 <-> p_15 can be inferred via the biconditional introduction rule. p_15 <-> q_10 can be inferred via the biconditional introduction rule. p_15 -> t can be inferred via the biconditional elimination rule. t -> p_15 can be inferred via the biconditional elimination rule. ~p_15 can be inferred via the biconditional elimination rule.