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 x_12: ~P(x_12). exists x_12: P(x_12) or U(x_12). forall x_12: U(x_12) <-> T_1(x_12).
exists x_12: U(x_12) can be inferred via the existential disjunctive syllogism rule. forall x_12: U(x_12) -> T_1(x_12) can be inferred via the universal biconditional elimination rule. forall x_12: T_1(x_12) -> U(x_12) can be inferred via the universal biconditional elimination rule.