Changes between Version 28 and Version 31 of Ticket #26355
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 10/08/19 08:49:44 (2 years ago)
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Ticket #26355

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sage8.9
tosage9.0
 Property Cc eric gourgoulhon added

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e9f8bba07c03da6e45bec04df721c115f4063959
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Ticket #26355 – Description
v28 v31 14 14 (See the book of Krishan L. Duggal and Aurel Bejancu in *REFERENCES*.) 15 15 16 In the present module, you can definie any of the 4 types but most of the 17 methods are implemented only for degenerate hypersurfaces who belong to 18 `r`lightlike submanifolds. However, their might be generalized to 19 `1`lightlike submanifolds. In the litterature there is a new approach 20 (the rigging technique) for studying `1`lightlike submanifolds but 21 here we we the method of Krishan L. Duggal and Aurel Bejancu base on 16 In the present module, one can define any of the 4 types but most of the methods are implemented only for degenerate hypersurfaces who belong to 17 `r`lightlike submanifolds. However, there might be generalized to 18 `1`lightlike submanifolds. In the literature, there is a new approach (the rigging technique) for studying `1`lightlike submanifolds but 19 here we the method of Krishan L. Duggal and Aurel Bejancu base on 22 20 the screen distribution. 23 21 … … 40 38 41 39 Tensors on the ambient manifold `M` are projected on `H` along `N` 42 to obtain induced objects. For instance, induced connection is the 43 linear connexion defined on `H` through the LeviCivitta connection of `g` along `N`. 40 to obtain induced objects. For instance, the induced connection is the linear connexion defined on `H` through the LeviCivitta connection of `g` along `N`. 44 41 45 To work on a degenerate submanifold, after defining `H` as an instance 46 of :class:`~sage.manifolds.differentiable.manifold.DifferentiableManifold`, 47 with the keyword *structure='degenerate_metric'*, you have to set a transvervector `v` and screen distribution together with the radical distribution. 42 To work on a degenerate submanifold, after defining `H` as an instance of :class:`~sage.manifolds.differentiable.manifold.DifferentiableManifold`, with the keyword *structure='degenerate_metric'*, you have to set a transvervector `v` and screen distribution together with the radical distribution. 48 43 49 44 An example of degenerate submanifold from General Relativity is the