What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? ~t. s_1 -> R_1(a_21). S_21(a_21) <-> t. S_21(a_21) -> R_1(a_21). forall x_21: R_1(x_21) -> S_21(x_21).
S_21(a_21) -> t. t -> S_21(a_21). ~S_21(a_21).