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: forall x: Q(x) <-> P(x). ~Q(i). P(i) <-> q_13.
P(i) -> q_13 can be inferred via the biconditional elimination rule. q_13 -> P(i) can be inferred via the biconditional elimination rule. forall x: Q(x) -> P(x) can be inferred via the universal biconditional elimination rule. forall x: P(x) -> Q(x) can be inferred via the universal biconditional elimination rule.