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JOURNALS // Uspekhi Matematicheskikh Nauk // Archive

Uspekhi Mat. Nauk, 2025 Volume 80, Issue 5(485), Pages 3–22 (Mi rm10261)

Multidimensional Hamiltonian systems: non-integrability and diffusion

V. V. Kozlov

Steklov Mathematical Institute of Russian Academy of Sciences, Moscow

Abstract: Hamiltonian systems of differential equations that are little different from completely integrable systems are under consideration. If such a system is integrable, then the action variables cannot change strongly, and there is no diffusion. Thus the non-integrable behaviour of a Hamiltonian system is closely linked with the diffusion of slow variables. This range of problems is discussed for a subclass of Hamiltonian systems. Using this example a new mechanism of diffusion, different from the ‘standard’ scheme of transition chains, is considered. This mechanism is related to the breakdown of a large number of invariant tori with almost resonance sets of frequencies of the non-perturbed problem. On the formal side, this phenomenon is based on the non-boundedness of integrals of conditionally-periodic functions of time with zero mean value.

Keywords: Hamiltonian system, main problem of dynamics, multivalued first integrals, Lindstedt series, diffusion, non-integrability, conditionally periodic functions.

UDC: 517.938+531.01

MSC: Primary 37J25; Secondary 37C75, 37J35

Received: 07.07.2025

DOI: 10.4213/rm10261


 English version:
Russian Mathematical Surveys, 2025, 80:5, 743–761

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© Steklov Math. Inst. of RAS, 2026