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 y: R_3(y) -> R_4(y). forall y: Q_4(y) -> R_3(y). forall y: R_4(y) <-> Q_4(y).
exists y: Q_4(y) -> R_4(y) can be inferred via the existential transitivity rule. forall y: R_4(y) -> Q_4(y) can be inferred via the universal biconditional elimination rule. forall y: Q_4(y) -> R_4(y) can be inferred via the universal biconditional elimination rule.