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González Gascón, F. and González López, Artemio
(1983)
*Symmetries of differential equations. IV.*
Journal of mathematical physics, 24
(8).
pp. 2006-2021.
ISSN 0022-2488

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Official URL: http://dx.doi.org/10.1063/1.525960

## Abstract

By an application of the geometrical techniques of Lie, Cohen, and Dickson it is shown that a system of differential equations of the form [x^(r_i)]_i = F_i(where r_i > 1 for every i = 1 , ... ,n) cannot admit an infinite number of pointlike symmetry vectors. When r_i = r for every i = 1, ... ,n, upper bounds have been computed for the maximum number of independent symmetry vectors that these systems can possess: The upper bounds are given by 2n_ 2 + nr + 2 (when r> 2), and by 2n_2 + 4n + 2 (when r = 2). The group of symmetries of ͞x^r = ͞0 (r> 1) has also been computed, and the result obtained shows that when n > 1 and r> 2 the number of independent symmetries of these equations does not attain the upper bound 2n _2 + nr + 2, which is a common bound for all systems of differential equations of the form ͞x^r = F[t, ͞x, ... , ͞x^(r - 1 )] when r> 2. On the other hand, when r = 2 the first upper bound obtained has been reduced to the value n^2 + 4n + 3; this number is equal to the number of independent symmetry vectors of the system ͞x= ͞0, and is also a common bound for all systems of the form ͞x = ͞F (t ,͞x, ‾̇x).

Item Type: | Article |
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Additional Information: | ©1983 American Institute of Physics. |

Uncontrolled Keywords: | Physics, Mathematical |

Subjects: | Sciences > Physics > Physics-Mathematical models Sciences > Physics > Mathematical physics |

ID Code: | 32931 |

Deposited On: | 28 Aug 2015 08:37 |

Last Modified: | 10 Dec 2018 15:10 |

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