Consider the following premises. For all x_11, if x_11 were a writer, then x_11 is fast. There is at least one x_11 for which x_11 is a sailor. For all x_11, x_11 is a writer or x_11 is not a sailor. Can we infer the following from them? If we can, name the inference rule being used: For all x_11, x_11 is not fast.
 From the fact that for all x_11, x_11 is a writer or x_11 is not a sailor we can infer that for all x_11, if x_11 were a sailor, then x_11 is a writer via universal rewriting. From the fact that for all x_11, if x_11 were a sailor, then x_11 is a writer, and that there is at least one x_11 for which x_11 is a sailor we can infer that there is at least one x_11 for which x_11 is a writer via existential modus ponens. Finally, from the fact that for all x_11, if x_11 were a writer, then x_11 is fast, and that there is at least one x_11 for which x_11 is a writer we can infer that there is at least one x_11 for which x_11 is fast via existential modus ponens, which contradicts that For all x_11, x_11 is not fast. Therefore, the answer is no.