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_1(f). forall z: R_1(z) <-> W(z). u or W(f).
~W(f) -> u can be inferred via the rewriting rule. forall z: R_1(z) -> W(z) can be inferred via the universal biconditional elimination rule. forall z: W(z) -> R_1(z) can be inferred via the universal biconditional elimination rule.