Feynman graphs and related Hopf algebras
  In a recent series of communications we have shown that the reordering problem of bosons leads to certain combinatorial structures. These structures may be associated with a certain graphical description. In this paper, we show that there is a Hopf Algebra structure associated with this problem which is, in a certain sense, unique. 
G\'erard Henry Edmond Duchamp (LIPN), Pawel Blasiak (LPTL), Andrzej   Horzela (LPTL), Karol A. Penson (LPTL), Allan I. Solom...