%0 Journal Article
%T Planar Shuffle Product, Co-Addition and the non-associative Exponential
%A Lothar Gerritzen
%J Mathematics
%D 2005
%I arXiv
%X In this note we introduce the concept of a shuffle product $\sq$ for planar tree polynomials and give a formula to compute the planar shuffle product $S \ \sq T$ of two finite planar reduced rooted trees $S, T.$ It is shown that $\sq$ is dual to the co-addition $\Delta$ which leads to a formula for the coefficients of $\Delta(f).$ It is also proved that $\Delta(EXP) = EXP {\hat \otimes} EXP$ where $EXP$ is the generic planar tree exponential series, see [G]. Systems of quadratic relations for the coefficients of EXP are derived.
%U http://arxiv.org/abs/math/0502378v1