Wiener-Wintner return-times ergodic theorem
The authors consider ergodic averages of the form \({1\over N} \sum e^{in\lambda} f'(S^n y). f(T^n x)\). They investigate how these averages are related to (and characterize) a new factor of the system (and its orthogonal) -- the maximal factor of the type ``Abelian group extension of a group rotation'' which satisfies a certain functional equation.
scientific article; zbMATH DE number 836175
scientific article