Abstract
Self-similar constructions of transformations preserving a sigma-finite measure are considered and their properties and the spectra of the induced Gaussian and Poisson dynamical systems are studied. The orthogonal operator corresponding to such a transformation has the property that some power of this operator is a nontrivial direct sum of operators isomorphic to the original one. The following results are obtained. For any subset \(M\) of the set of positive integers, in the class of Poisson suspensions, sets of spectral multiplicities of the form \(M\cup\{\infty\}\) are realized. A Gaussian flow \(S_t\) is presented such that the set of spectral multiplicities of the automorphisms \(S_{p^{n}}\) is \(\{1,\infty\}\) if \(n\le 0\) and \(\{p^n,\infty\}\) if \(n> 0\). A Gaussian flow \(T_t\) such that the automorphisms \(T_{p^{n}}\) have distinct spectral types for \(n\le 0\) but all automorphisms \(T_{p^{n}}\), \(n>0\), are pairwise isomorphic is constructed.
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Translated from Matematicheskie Zametki, 2023, Vol. 113, pp. 273–282 https://doi.org/10.4213/mzm13500.
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Ryzhikov, V.V. Spectra of Self-Similar Ergodic Actions. Math Notes 113, 274–281 (2023). https://doi.org/10.1134/S0001434623010303
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DOI: https://doi.org/10.1134/S0001434623010303