We give algebraic formulas for the minimal intersection and self-intersection numbers of proper arcs and curves on oriented surfaces. In the case of closed curves, the formulas are given in terms of the Andersen-Mattes-Reshetikhin Poisson algebra of chord diagrams on a surface, and a related operation $\mu$. The operation $\mu$ can be viewed as a generalization of Turaev's Lie coalgebra structure on the vector space generated by nontrivial free homotopy classes of loops on a surface. Some of the work presented is jointwith Vladimir Chernov.
Links:
[1] http://www.mpim-bonn.mpg.de/taxonomy/term/39
[2] http://www.mpim-bonn.mpg.de/node/3444
[3] http://www.mpim-bonn.mpg.de/node/5019