4 years, 54 days

## How do I use simplification correctly?...

Maple 2018

Hello!

I am truing to simplify kretchmann variable in the following worksheet:

 M > # Obtaining Ricci and Kretchmann; with(DifferentialGeometry):with(Tensor):
 > DGsetup([t, r, theta, phi], M); g := evalDG(-(1-2*M*mu/r)^(1/mu)*dt &t dt+(1-2*M*mu/r)^(-1/mu)*&t(dr, dr)+r^2*(1-2*M*mu/r)^(1-1/mu)*(&t(dtheta, dtheta)+sin(theta)^2*&t(dphi, dphi))); C := Christoffel(g):
 (1.1)

Rie := CurvatureTensor(C):
R := RicciScalar(g,Rie);
h := InverseMetric(g):
kretchmann := ContractIndices(RaiseLowerIndices(g, Rie, [1]), RaiseLowerIndices(h, Rie, [2, 3, 4]), [[1, 1], [2, 2], [3, 3], [4, 4]]);

 (1.2)
 M > # simplification
 M > simplify(normal(R),symbolic)
 (1.3)
 M > simplify(kretchmann,size,symbolic)
 (1.4)
 M >

The problem is that I cannot obtain a good form of it. With Mathematica FullSimplify[] function I got the following form (LaTeX code incoming): $K =& 4 M^2 \Bigl(A-B r+C r^2\Bigr)(r-2 M \mu)^{\frac{2}{\mu}-4}r^{-\frac{2}{\mu}-4},\ A =&M^2 (\mu (3 \mu+2)+7) (\mu+1)^2,\,B = 8 M (\mu+2) (\mu+1),\, C = 12$, i.e. terms $(r-2 M \mu)$ and $r$ got fully factorized. However, I could never achieve the same form in Maple. Any help?

I am sorry if this is a silly and many-times-answered question, but I tried consulting with Maple help and googling solutions without any success.

Regards,
Nick

## How do I unprotect x in Killing vectors?...

Maple 2018

Hello!

I am trying to determine the type of Lie algebra originating from Killing vectors. However, Maple says that some variable x is protected (though, I guess, it shouldn't even be in the L). Is there any way to solve this issue?

Best regards,
Nick

error.mw

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## Error when finding Killing Vectors in Ma...

Maple

Hello!

I tried to find Killing vectors of a certain metric, but Maple gives an error, which is reproduced with the following piece of code (the metric which I need is more difficult, so I would like to refrain from using "Physics" package). Could anybody tell me what the problem is and how I should solve it, please?

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