At the centre of this workshop’s logo sits the Tutte polynomial. The Tutte polynomial’s raison d’être is to serve as the universal invariant of graphs, or more generally matroids, which satisfies the deletion–contraction relations. Normally these relations are set up with three recursive cases, according as the selected element is a loop, a bridge, or neither, plus a base case. Products appear for loops and bridges, and the universality is formulated accordingly.