  Graph cocycles for star-products are investigated from the combinatorial
point of view, using Connes-Kreimer renormalization techniques.
  The Hochschild complex, controlling the deformation theory of associative
algebras, is the ``Kontsevich representation'' of a DGLA of graphs coming from
a pre-Lie algebra structure defined by graph insertions.
  Properties of the dual of its UEA (an odd parity analog of Connes-Kreimer
Hopf algebra), are investigated in order to find solutions of the deformation
equation. The solution of the initial value deformation problem, at tree-level,
is unique. For linear coefficients the resulting formulas are relevant to the
Hausdorff series.
