Consider the following premises. For all y_3, y_3 is an electrician if and only if y_3 will go running. Jessica is an electrician. Can we infer the following from them? There is at least one y_3 for which y_3 will go running.
 From the fact that for all y_3, y_3 is an electrician if and only if y_3 will go running we can infer that for all y_3, if y_3 were an electrician, then y_3 is running. From the fact that Jessica is an electrician we can infer that there is at least one y_3 for which y_3 is an electrician. Finally, from the fact that for all y_3, if y_3 were an electrician, then y_3 is running, and that there is at least one y_3 for which y_3 is an electrician we can infer that there is at least one y_3 for which y_3 will go running. Therefore, the answer is yes.