http://math.stanford.edu/theses/tarn_thesis.pdf "Flat Chains in Banach Spaces"
I am not a person who thinks that genius should ever be measured with one sole trait, unlike my one friend who dismissed the entire field of biology being "a real science" because it "doesn't use math" - he then proceed to dismiss tons of other fields as "not real science", moving eventual into the social sciences like linguistics and psychology before I told him to shut up (and in my head, punched him in the face).
We already recognized Tarn as a genius because of our love of the complexity the game. Dwarf Fortress does not exist in a one-field vacuum, simply being an amazing coder does nothing if you have no idea of what to code. DF is an amalgam of sources scientific, historical, mythological, literary and so on. But reading his thesis (and by read I mean skim because I got 51 is grade 10 math and can barely multiply without using my fingers), it's really cool to see one aspect of his brain distilled - in this case his incredible facility with mathematics. I think we all ought to glance over this work of mind-numbing complexity and give thanks that Tarn chose aim his genius away from such academic work, where he would no doubt have prospered, and instead taken the time to bestow on us the amazing thing that is Dwarf Fortress.