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: u -> W_1(a_5). forall x: W_1(x) <-> S(x). u or S(a_5).
R_1(a_5) -> u can be inferred via the rewriting rule. forall x: W_1(x) -> S(x) can be inferred via the universal biconditional elimination rule. forall x: S(x) -> W_1(x) can be inferred via the universal biconditional elimination rule.