A good chunk of us who have just seen Inception have started debating over whether Leonardo DiCaprio’s character Cobb is still stuck in the dream world. The film’s final shot is his totem spinning on the table and before we see if it topples (a sign of being in the real world), it cuts to black.
Throughout the film we regularly see flashes of Cobb’s children as he remembers them right before he goes on the run. His young daughter appears in a light red dress and his son in some plaid shirt. Now, if we are to apply the A Beautiful Mind theorem, we might be able to deduce whether Cobb is awake or dreaming.