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: R(y). forall y: U_2(y). forall y: P(y) <-> R(y).
forall y: R(y) and U_2(y) can be inferred via the universal conjunction rule. forall y: U_2(y) and R(y) can be inferred via the universal conjunction rule. forall y: P(y) -> R(y) can be inferred via the universal biconditional elimination rule. forall y: R(y) -> P(y) can be inferred via the universal biconditional elimination rule.