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The infinitesimal Hopf algebra and the operads of planar forestsLoïc Foissy
To cite this version:Loïc Foissy. The infinitesimal Hopf algebra and the operads of planar forests. 2009. hal-00353236The infinitesimal Hopf algebra and the operads of planar forests ABSTRACT. We introduce two operads which own the set of planar forests as a basis. With its usual product and two other products defined by different types of graftings, the algebra of planar rooted trees H becomes an algebra over these operads. The compatibility with the infinitesimal coproduct of H and these structures is studied. As an application, an inductive way of computing the dual basis of H for its infinitesimal pairing is given. Moreover, three Cartier-Quillen-Milnor-Moore theorems are given for the operads of planar forests and a rigidity theorem for one of them.