Consider the following premises. If Richard were an electrician, then Michael is fast. If Michael were fast, then it is sunny. If Jennifer plays squash, then Richard is an electrician. If it is sunny, then Jennifer is playing squash. Can we infer the following from them? If we can, name the inference rule being used: If is not true that it is sunny if and only if Richard is an electrician.
 From the fact that if it is sunny, then Jennifer is playing squash, and that if Jennifer plays squash, then Richard is an electrician we can infer that if it is sunny, then Richard is an electrician via transitivity. From the fact that if Richard were an electrician, then Michael is fast, and that if Michael were fast, then it is sunny we can infer that if Richard were an electrician, then it is sunny via transitivity. Finally, from the fact that if it is sunny, then Richard is an electrician, and that if Richard were an electrician, then it is sunny we can infer that it is sunny if and only if Richard is an electrician via biconditional introduction, which contradicts that If is not true that it is sunny if and only if Richard is an electrician. Therefore, the answer is no.