**Keynote Speaker:****C****hen Shaoshi**

**Abstract:**

In this work, we introduce a class of sequences, so-called dynamical sequences, which are defined by rational dynamical systems over algebraic varieties. Many classical sequences from number theory and algebraic combinatorics fall under this dynamical framework. For a dynamical sequence a(n), we show that the set of n for which a(n) is in a finitely generated group is a finite union of arithmetic progressions along with a set of zero Banach density. This result generalizes the classical Skolem-Mahler-Lech theorem for sequences satisfying linear recurrence relations. We apply this dynamical approach to prove a rationality theorem on D-finite power series.

**Speaker Introduction:**

Chen Shaoshi, the Associate Researcher and Doctoral Supervisor of Academy of Mathematics and Systems Science, Chinese Academy of Sciences, is mainly engaged in researches on symbolic computation, computing differential algebra and combinatorial mathematics. In 2011, he graduated as the doctoral student in the cooperative doctoral candidate education program of Chinese Academy of Sciences and France Paris Polytechnic (École Polytechnique). He was admitted as a doctoral candidate by the Institute of Symbolic Computation of Johannes Kepler University Linz in Austria, North Carolina State University in America, Fields Institute for Research in Mathematical Sciences in Canada, and Research Group of Symbolic Computation in Waterloo. In 2013, he returned to work in the Institute of Systems Science, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, and was promoted to an Associate Researcher in 2017. He has presided over Young Scientists Fund of National Natural Science Foundation of China and general fund. He has published 14 articles in ISSAC (International Symposium on Symbolic and Algebraic Computation) and more than 10 articles in such journals as*Algebra and Number Theory*,*Journal of Symbolic Computation*,*Journal of Algebra*,*Journal of Combinatorial Theory*,*Series A*, etc. Now, he is the Associate Editor of*Annals of Combinatorics*(an international journal in combinatorics),*ACM Communications in Computer Algebra*of International Committee of Symbolic and Algebraic Computation,*Journal of Systems Science and Complexity, Systems Science and Mathematics*, etc. Since 2019, he has been a Standing Committee Member of the steering committee of ISSAC. He was rated the "Outstanding Scientific Research Achievement Award in 2014" of Academy of Mathematics and Systems Science, Chinese Academy of Sciences, "Important Scientific Research Progress Award in 2018" and the Second "Wu Wen-tsün Computer Mathematics Young Scholar Award". He was selected as a member of the Seventh "Chen Jingrun Future Star" Talent Scheme of Chinese Academy of Sciences and Youth Innovation Promotion Association CAS in 2018.

**Inviter:**

Wang Guanghui ProfessorofSchool of Mathematics

**Time:**

15:00-16:30 on March 10 (Wednesday)

**Location:**

Tencent Meeting, Meeting ID: 422 186 105,Password:123456

**Hosted by: School of Mathematics, Shandong University**