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: r <-> t. t <-> S_12(a_12). forall x_12: R_12(x_12) <-> S_12(x_12). ~R_12(a_12).
r -> t can be inferred via the biconditional elimination rule. t -> S_12(a_12) can be inferred via the biconditional elimination rule. t -> r can be inferred via the biconditional elimination rule. S_12(a_12) -> t can be inferred via the biconditional elimination rule. forall x_12: R_12(x_12) -> S_12(x_12) can be inferred via the universal biconditional elimination rule. forall x_12: S_12(x_12) -> R_12(x_12) can be inferred via the universal biconditional elimination rule.