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: forall y: U_4(y) -> Q(y). exists y: U_4(y) <-> Q(y).
exists y: U_4(y) -> Q(y) can be inferred via the existential biconditional elimination rule. exists y: Q(y) -> U_4(y) can be inferred via the existential biconditional elimination rule.