Traversing regions of supersolvable hyperplane arrangements and their lattice quotients
By Torsten Mütze
Extending the ab-index for braid and reflection arrangements
By Christian Stump
Appears in collection : Algebraic Structures in Perturbative Quantum Field Theory: a conference in honour of Dirk Kreimer's 60th birthday
We describe how certain analytic Dyson-Schwinger equations and related tree-like equations arise from the universal property of the Connes-Kreimer Hopf algebra applied to Hopf subalgebras obtained from combinatorial Dyson-Schwinger equations in the work of Foissy. We then show how these equations can be solved as weighted generating functions of certain classes of chord diagrams and obtain an explicit formula counting some of these combinatorial objects.