Here is a preprint about baseball. We believe that in certain certain situations, baserunners should be more aggressive on the base paths. It is joint work with Peter MacDonald and Ian McQuillan.

Our proof that every drawing of the complete graph in the plane must have at least 219 crossings is summarized here. It is joint work with S. Pan and R. B. Richter.

This preprint, *Witt cancellation seen as a cancellation*, is on the Witt Cancellation Theorem, with extra information about the Witt Ring. It is joint work with Sunil Chebolu and Ján Mináč. The illustrations are by Matthew Teigen.

Here are the slides for my talk, “*Vertex-magic graphs*,” from June 11, 2011, at the spring meeting of the Northeastern Section of the Mathematical Association of America.