Expository papers

• An introduction to cobordism theory (ps pdf) My minor thesis, written under the supervision of Raoul Bott and Franklin Peterson. Nothing terribly original here, although I think that, as these things go, it's a fairly painless introduction to the subject.
• The Banach-Tarski paradox (ps pdf) An extra-explicit exposition of this well-known result. The highlight, from a purely visual standpoint, is pages 10 and 11.
• The inflation-restriction sequence: an introduction to spectral sequences (ps pdf) A quick introduction to spectral sequences. My most popular paper, for some reason. I suspect that it's the pictures.
• The modular curves X₀(11) and X₁(11) (ps) An introduction to modular curves focused on the motivating problem of analyzing rational 11-torsion on elliptic curves. It originated in some notes of Matthew Emerton and some computations of Keith Conrad and Robert Pollack, and ostensibly had some connection to the 1999 Park City Mathematics Institute.
• L-functions and cyclotomic units (ps pdf) A write-up of a lecture on Euler systems I gave at the 2001 Arizona Winter School.
• The Euler system of Heegner points (ps pdf) An exposition of Kolyvagin's work on the conjecture of Birch and Swinnerton-Dyer, inspired by a student project I supervised at the 2001 Arizona Winter School.
• Lectures on the Dirichlet class number formula for imaginary quadratic fields (ps pdf) A write-up of some lectures I gave at the Ross program in the summer of 2004.