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(y) -> R(y). exists y: R(y) -> U_1(y). forall y: U_1(y) -> R(y). forall y: U(y) <-> W(y). forall y: U_1(y) or W(y).
exists y: U(y) -> U_1(y) can be inferred via the existential transitivity rule. exists y: R(y) <-> U_1(y) can be inferred via the existential biconditional introduction rule. exists y: U_1(y) <-> R(y) can be inferred via the existential biconditional introduction rule. forall y: U(y) -> W(y) can be inferred via the universal biconditional elimination rule. forall y: W(y) -> U(y) can be inferred via the universal biconditional elimination rule.