Abstract
Exploiting the recent work of Tao and Ziegler on the concatenation theorem on factors, we find explicit characteristic factors for multiple averages along polynomials on systems with commuting transformations, and use them to study criteria of joint ergodicity for sequences of the form \((T_{1}^{p_{1,j}(n)}\cdots T_{d}^{p_{d,j}(n)})_{n\in\mathbb{Z}}\), 1 ≤ j ≤ k, where T1, …, Td are commuting measure preserving transformations on a probability measure space and pi, j are integer polynomials. To be more precise, we provide a sufficient condition for such sequences to be jointly ergodic, giving also a characterization for sequences of the form \((T_{i}^{p(n)})_{n\in\mathbb{Z}}\), 1 ≤ i ≤ d to be jointly ergodic, answering a question due to Bergelson.
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The first author is supported by ANID/Fondecyt/1200897 and Centro de Modelamiento Matemático (CMM), ACE210010 and FB210005, BASAL funds for centers of excellence from ANID-Chile.
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Donoso, S., Koutsogiannis, A. & Sun, W. Seminorms for multiple averages along polynomials and applications to joint ergodicity. JAMA 146, 1–64 (2022). https://doi.org/10.1007/s11854-021-0186-z
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DOI: https://doi.org/10.1007/s11854-021-0186-z