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: S_1(f) <-> W(f). forall z_4: W(z_4) <-> S_1(z_4).
S_1(f) -> W(f) can be inferred via the biconditional elimination rule. W(f) -> S_1(f) can be inferred via the biconditional elimination rule. forall z_4: W(z_4) -> S_1(z_4) can be inferred via the universal biconditional elimination rule. forall z_4: S_1(z_4) -> W(z_4) can be inferred via the universal biconditional elimination rule.