What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? r <-> S_13(a_13). ~r_2 or R_13(a_13). r_2 or r. forall x_13: R_13(x_13) -> S_13(x_13).
r or R_13(a_13). R_1(a_13) -> ~r_2. r -> S_13(a_13). S_13(a_13) -> r.