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. u_1 <-> q_15. ~u_1. t -> p.
~t can be inferred via the modus tollens rule. ~p and ~u_1 can be inferred via the conjunction rule. ~u_1 and ~p can be inferred via the conjunction rule. u_1 -> q_15 can be inferred via the biconditional elimination rule. q_15 -> u_1 can be inferred via the biconditional elimination rule. ~q_15 can be inferred via the biconditional elimination rule.