Consider the following premises. For all x_11, x_11 is a mechanic. There is at least one x_11 for which x_11 is rich. For all x_11, x_11 is a scientist or x_11 is not rich. Can we infer the following from them? If we can, name the inference rule being used: Some mechanics are scientists.
 From the fact that for all x_11, x_11 is a scientist or x_11 is not rich we can infer that for all x_11, if x_11 were rich, then x_11 is a scientist via universal rewriting. From the fact that for all x_11, if x_11 were rich, then x_11 is a scientist, and that there is at least one x_11 for which x_11 is rich we can infer that there is at least one x_11 for which x_11 is a scientist via existential modus ponens. Finally, from the fact that for all x_11, x_11 is a mechanic, and that there is at least one x_11 for which x_11 is a scientist we can infer that some mechanics are scientists via existential conjunction. Therefore, the answer is yes.