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math-ph2025
Solutions of Three-Dimensional Stationary Gas Dynamics Equations
O. V. Kaptsov
This paper examines the three-dimensional stationary equations of a polytropic gas and employs symmetry methods to construct exact analytical solutions. In the Chaplygin gas case,…
math.DS2025
Exponential map of germs of vector fields
Oleg Kaptsov
In this paper we introduce an exponential map of the algebra of germs of vector fields into the group of germs of diffeomorphisms at zero. It is shown that this mapping is not a bi…