Vladimir, there's plenty of non-trivial decision theory math that other people have invented.

If I were going to write up a piece of novel FAI math, it would be my general theory of Newcomblike problems, but the last time I tried that it started turning into a book. But that would be the main thing that I would do, if it got to the point that impressing people with at least one piece of elegant math turned into a high enough priority.