Consider the following premises. Charles is bored if and only if James is an electrician. Sarah is playing tennis if and only if Richard is a lawyer. For all y, y will write a letter if and only if y will play tennis. Charles is not bored. If Richard were a lawyer, then James is an electrician. Can we infer the following from them? Sarah is not writing a letter.
 From the fact that Charles is bored if and only if James is an electrician, and that Charles is not bored we can infer that James is not an electrician. From the fact that if Richard were a lawyer, then James is an electrician, and that James is not an electrician we can infer that Richard is not a lawyer. From the fact that for all y, y will write a letter if and only if y will play tennis we can infer that Sarah is writing a letter if and only if Sarah is playing tennis. From the fact that Sarah is playing tennis if and only if Richard is a lawyer, and that Richard is not a lawyer we can infer that Sarah is not playing tennis. Finally, from the fact that Sarah is writing a letter if and only if Sarah is playing tennis, and that Sarah is not playing tennis we can infer that Sarah is not writing a letter. Therefore, the answer is yes.