As inadvertently blogged below, I'm back in Oxford this week, pretending to be a computer scientist (or at least a software engineer) once more. I already established that one of the other guys had to be an instance of a specialization of me, since he could finish a milkshake in less time than me. (The post-condition of a subclass operation, like a class invariant, can be stronger than the superclass version, or equally strong but never weaker. The principle is called covariance. Any practicing programmer knows about polymorphism and the like, but übergeeks take things to another level.)
(Despite what it says below, this post has comments...)