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_11, x_11 is not rich. If Joseph were a taxi driver, then Mary is not writing a letter. For all x_11, x_11 is rich or x_11 will write a letter.
For all x_11, x_11 will write a letter can be inferred via the universal disjunctive syllogism rule.