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: For all x_1, if x_1 were fast, then x_1 is poor. For all x_1, if x_1 were a taxi driver, then x_1 is not poor. For all x_1, x_1 is fast.
For all x_1, x_1 is poor can be inferred via the universal modus ponens rule.