Expository and recreational writing

• A combinatorial card trick
  (with Shai Simonson) PRIMUS XIII no. 3 (2003) 248--269.
  Available in PDF.
  We describe the combinatorics underlying a cute card trick.  We wrote an extended problem set about this card trick for our Discrete Mathematics course, and we follow the students' experiences grappling with it.
  
  
• Kirwan surjectivity for preorbifold cohomology
  (with Rebecca Goldin and Allen Knutson) Cohomological aspects of Hamiltonian group actions, Mathematisches Forschungsinstitut Oberwolfach Report no. 20 (2004) 36--39.
  Available in PDF
  This is essentially an announcement of some results that we are currently writing up.

• Symmetries of parking lots
  (with Dan Isaksen) in preparation.
  This is a cute problem we worked out while at the Duluth REU.  We study which wall paper groups can show up as the symmetry groups of parking lots.  We have the paper written in some very condensed form, and neither of us has had the time in recent years to put it into publishable shape.