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: exists x: ~S_3(x). forall x: Q(x) <-> S_3(x). forall x: Q(x) -> S_3(x).
exists x: ~Q(x) can be inferred via the existential modus tollens rule. forall x: Q(x) -> S_3(x) can be inferred via the universal biconditional elimination rule. forall x: S_3(x) -> Q(x) can be inferred via the universal biconditional elimination rule. exists x: ~Q(x) can be inferred via the existential biconditional elimination rule.