Consider the following premises. There is at least one x_11 for which if x_11 were a sailor, then x_11 is an electrician. For all x_11, if x_11 were an electrician, then x_11 is working. For all x_11, x_11 will take a plane. For all x_11, if x_11 takes a plane, then x_11 is working. For all x_11, if x_11 works, then x_11 is an electrician. Can we infer the following from them? If we can, name the inference rule being used: For all x_11, x_11 is not an electrician.
 From the fact that for all x_11, if x_11 were an electrician, then x_11 is working, and that for all x_11, if x_11 works, then x_11 is an electrician we can infer that for all x_11, x_11 is an electrician if and only if x_11 will work via universal biconditional introduction. From the fact that for all x_11, x_11 will take a plane we can infer that for all x_11, x_11 will take a plane or x_11 is a sailor via universal addition. From the fact that for all x_11, x_11 is an electrician if and only if x_11 will work we can infer that for all x_11, if x_11 works, then x_11 is an electrician via universal biconditional elimination. From the fact that for all x_11, if x_11 takes a plane, then x_11 is working, and that for all x_11, if x_11 works, then x_11 is an electrician we can infer that for all x_11, if x_11 takes a plane, then x_11 is an electrician via universal transitivity. Finally, from the fact that for all x_11, if x_11 takes a plane, then x_11 is an electrician, that there is at least one x_11 for which if x_11 were a sailor, then x_11 is an electrician, and that for all x_11, x_11 will take a plane or x_11 is a sailor we can infer that there is at least one x_11 for which x_11 is an electrician via existential disjunction elimination, which contradicts that For all x_11, x_11 is not an electrician. Therefore, the answer is no.