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math-ph2026

Symmetry analysis and exact solutions of multi-layer quasi-geostrophic problem

Serhii D. Koval, Alex Bihlo, Roman O. Popovych

We carry out an extended symmetry analysis of the multi-layer quasi-geostrophic problem. This model is given by a system of an arbitrary number of coupled barotropic vorticity equa…

math-ph2025

Surprising symmetry properties and exact solutions of Kolmogorov backward equations with power diffusivity

Serhii D. Koval, Elsa Dos Santos Cardoso-Bihlo, Roman O. Popovych

Using the original advanced version of the direct method, we efficiently compute the equivalence groupoids and equivalence groups of two peculiar classes of Kolmogorov backward equ…

math-ph2025

Generalized symmetries of remarkable (1+2)-dimensional Fokker-Planck equation

Dmytro R. Popovych, Serhii D. Koval, Roman O. Popovych

Using an original method, we find the algebra of generalized symmetries of a remarkable (1+2)-dimensional ultraparabolic Fokker-Planck equation, which is also called the Kolmogorov…

math-ph2025

Subalgebras of Lie algebras. Example of sl(3,R) revisited

Yevhenii Yu. Chapovskyi, Serhii D. Koval, Olha Zhur

Revisiting the results by Winternitz [Symmetry in physics, CRM Proc. Lecture Notes 34, American Mathematical Society, Providence, RI, 2004, pp. 215-227], we thoroughly refine his c…

math-ph2024

Extended symmetry analysis of (1+2)-dimensional fine Kolmogorov backward equation

Serhii D. Koval, Roman O. Popovych

Within the class of (1+2)-dimensional ultraparabolic linear equations, we distinguish a fine Kolmogorov backward equation with a quadratic diffusivity. Modulo the point equivalence…