What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall y: P(y) -> Q(y). forall y: T_4(y) <-> P(y). forall y: Q(y) -> P(y). exists y: ~T_4(y).
forall y: P(y) <-> Q(y). forall y: Q(y) <-> P(y). forall y: T_4(y) -> P(y). forall y: P(y) -> T_4(y). exists y: ~P(y).