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_2: U_1(y_2) <-> U_2(y_2). forall y_2: U_1(y_2).
exists y_2: U_1(y_2) -> U_2(y_2) can be inferred via the existential biconditional elimination rule. exists y_2: U_2(y_2) -> U_1(y_2) can be inferred via the existential biconditional elimination rule.