Natural endomorphisms of quasi-shuffle Hopf algebras
Natural endomorphisms of quasi-shuffle Hopf algebras
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DOI:
10.24033/bsmf.2644
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发表时间:
2011-01
期刊:
影响因子:
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通讯作者:
J. Novelli;F. Patras;J. Thibon
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文献类型:
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作者:
J. Novelli;F. Patras;J. Thibon
The Hopf algebra of word-quasi-symmetric functions ($\WQSym$), a noncommutative generalization of the Hopf algebra of quasi-symmetric functions, can be endowed with an internal product that has several compatibility properties with the other operations on $\WQSym$. This extends constructions familiar and central in the theory of free Lie algebras, noncommutative symmetric functions and their various applications fields, and allows to interpret $\WQSym$ as a convolution algebra of linear endomorphisms of quasi-shuffle algebras. We then use this interpretation to study the fine structure of quasi-shuffle algebras (MZVs, free Rota-Baxter algebras...). In particular, we compute their Adams operations and prove the existence of generalized Eulerian idempotents, that is, of a canonical left-inverse to the natural surjection map to their indecomposables, allowing for the combinatorial construction of free polynomial generators for these algebras.