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: S_2(a_1). forall y: S_2(y) <-> T_3(y).
exists x: S_2(x) can be inferred via the existential generalization rule. forall y: S_2(y) -> T_3(y) can be inferred via the universal biconditional elimination rule. forall y: T_3(y) -> S_2(y) can be inferred via the universal biconditional elimination rule.