Abstract
Using the extension method, we study the one-parameter symmetry groups of the heat equation ∂tp = Δp, where \(\Delta=X_1^2+X_2^2\) is the sub-Laplacian constructed by a Goursat distribution span({X1, X2}) in ℝn, where the vector fields X1 and X2 satisfy the commutation relations [X1, Xj] = Xj+1 (where Xn+1 = 0) and [Xj, Xk] = 0 for j ≥ 1 and k ≥ 1. We show that there are no such groups for n ≥ 4 (with exception of the linear transformations of solutions which are admitted by every linear equation).
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The author was supported by the Ministry of Education and Science of the Russian Federation (Grant 1.12875.2018/12.1).
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Translated from Sibirskii Matematicheskii Zhurnal, vol. 60, no. 1, pp. 141–148, January–February, 2019; DOI: 10.17377/smzh.2019.60.112.
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Kuznetsov, M.V. Absence of Nontrivial Symmetries to the Heat Equation in Goursat Groups of Dimension at Least 4. Sib Math J 60, 108–113 (2019). https://doi.org/10.1134/S0037446619010129
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DOI: https://doi.org/10.1134/S0037446619010129