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: T_2(y) -> S_4(y). forall y: T_2(y) <-> S_4(y).
forall y: T_2(y) -> S_4(y) can be inferred via the universal biconditional elimination rule. forall y: S_4(y) -> T_2(y) can be inferred via the universal biconditional elimination rule.