What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? ~r_1. r_1 or ~r_4. r_4 <-> r_1. r.
~r_4. ~r_1 and r. r and ~r_1. r_4 -> r_1. r_4 -> r_1. r_1 -> r_4. ~r_4.