Consider the following premises. For all y, y is a sailor. For all y, if y were a janitor, then y is taking a plane. For all y, y is a janitor or y will drive a car. For all y, if y drives a car, then y is taking a plane. Can we infer the following from them? If we can, name the inference rule being used: There is at least one y for which y will not take a plane.
 From the fact that for all y, if y were a janitor, then y is taking a plane, that for all y, if y drives a car, then y is taking a plane, and that for all y, y is a janitor or y will drive a car we can infer that for all y, y will take a plane via universal disjunction elimination. From the fact that for all y, y is a sailor, and that for all y, y will take a plane we can infer that for all y, y is a sailor and y will take a plane via universal conjunction. Finally, from the fact that for all y, y is a sailor and y will take a plane we can infer that for all y, y is a sailor via universal simplification, which contradicts that There is at least one y for which y will not take a plane. Therefore, the answer is no.