Consider the following premises. For all x_6, if x_6 sleeps, then x_6 is happy. For all x_6, x_6 is a janitor if and only if x_6 is happy. For all x_6, if x_6 were a janitor, then x_6 is sleeping. Can we infer the following from them? For all x_6, if x_6 were a janitor, then x_6 is happy.
Yes.