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MATHEMATICS
Conical singular points and vector fields
S. N. Bur'yan St. Petersburg State University, 7-9, Universitetskaya nab., St. Petersburg, 199034, Russian Federation
Abstract:
In this article, several examples of mechanical systems which configuration spaces are smooth manifolds with a unique singular point are considered. Configuration spaces are the following: two smooth curves with a common point (or tangent) on the two-dimensional torus, four smooth curves on the four-dimensional torus with a common point, twodimensional cone (cusp) in the space $R^6$. The main problem in the article is the calculation of (co)tangent space at a singular point by using different theoretical approaches. Outside of the singular point, the motion could be described in the frames of classical mechanics. But in the neighborhood of the singular points the terms like "tangent vector" and "cotangent vector" must have new conceptual definitions. In this article, the approach of differential spaces is used. Two differential structures for the modeling conical singular point are studied in order to construct (co)tangent space at singular points: locally-constants functions near to the cone vertex and the algebra of the restrictions of smooth functions in the comprehensive Euclidean space on the cone. In the first case, tangent and cotangent spaces at the singular points are zero. In the second case, the value of the functions on the cotangent bundle is constant on the cotangent layer under the singular point.
Keywords:
singular point, manifolds with conical singularities, differential spaces.
Received: 01.09.2020 Revised: 08.07.2020 Accepted: 18.07.2020
Citation:
S. N. Bur'yan, “Conical singular points and vector fields”, Vestnik of Saint Petersburg University. Mathematics. Mechanics. Astronomy, 7:4 (2020), 649–661
Linking options:
https://www.mathnet.ru/eng/vspua153 https://www.mathnet.ru/eng/vspua/v7/i4/p649
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