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Weak quasisymmetric functions and RotaBaxter algebras
喻厚义 副教授(西南大学)
Friday, April 19th, 2019, 4:00 PM 闵行数学楼402报告厅 

摘要： We introduce the Hopf algebra of quasisymmetric functions with semigroup exponents generalizing the Hopf algebra QSym of quasisymmetric functions. As a special case we obtain the Hopf algebra WQSym of weak quasisymmetric functions, which provides a framework for the study of a question proposed by G.C. Rota relating symmetric type functions and Rota?Baxter algebras. We show that QSym is a Hopf subalgebra and a Hopf quotient algebra of WQSym. Rota’s question is addressed by identifying WQSym with the free commutative unitary Rota?Baxter algebra of weight 1 on one generator, which also allows us to equip the latter with a Hopf algebra structure. This is joint work with Li Guo, JeanYves Thibon, and Jianqiang Zhao.



