Consider the following premises. Richard is an electrician if and only if Susan is a soldier. If Richard were excited, then Richard is an electrician. Richard is excited or Susan is a soldier. Can we infer the following from them? If we can, name the inference rule being used: Richard is not an electrician.
 From the fact that Richard is an electrician if and only if Susan is a soldier we can infer that if Susan were a soldier, then Richard is an electrician via biconditional elimination. Finally, from the fact that if Richard were excited, then Richard is an electrician, that if Susan were a soldier, then Richard is an electrician, and that Richard is excited or Susan is a soldier we can infer that Richard is an electrician via disjunction elimination, which contradicts that Richard is not an electrician. Therefore, the answer is no.