Consider the following premises. For all y_3, y_3 is not an office clerk. Patricia is an office clerk. Can we infer the following from them? Karen is a writer.
 From the fact that for all y_3, y_3 is not an office clerk we can infer that Patricia is not an office clerk. From the fact that Patricia is an office clerk we can infer that Patricia is an office clerk or Karen is a writer. Finally, from the fact that Patricia is an office clerk or Karen is a writer, and that Patricia is not an office clerk we can infer that Karen is a writer. Therefore, the answer is yes. Notice, however, that the premises were contradictory, so we can infer anything from them.