Symbolic manipulation program required

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The discussion centers on the use of GRtensor for symbolic manipulation in general relativity, highlighting the necessity of specifying a metric for calculations. Users inquire about alternatives that allow symbolic manipulation without a defined metric, noting that this limitation affects operations like raising and lowering indices. The Excalc package in Reduce is suggested as a potential alternative for those seeking different capabilities. There is also a question regarding the feasibility of using arbitrary variables for the metric in GRtensor without specifying explicit forms. Overall, the conversation seeks clarity on tools for proving general identities in general relativity without reliance on specific metrics.
krishna mohan
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Hi...

I have just started using GRtensor...
I realize that the calculations in GRtensor have to be done only after specifying a metric...

Is there any package which can directly do symbolic manipulation without using the metric?
 
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As far as I know, you always have to specify a metric in symbolic manipulation software. Otherwise the software would not know how to "raise" and "lower" indices of vectors, tensors, etc. Of course you always have the possibility to leave the components of the metric as unknown functions.

If you look for an alternative of GRTensor you could try th Excalc package in Reduce: http://www.uni-koeln.de/REDUCE/3.6/doc/excalc/"
 
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What sort of manipulations are you looking for? GRTensor makes it easy to manipulate a metric, which you can make as general as you like, Maple makes it easy to manipulate other mathematical thigns like ordinary and differential equations, plus a bunch of other things.

So I'm not getting a clear picture of what you're looking for...
 
I have to prove some general identities in GR...and not for a particular metric..

In GRtensor, can we put a metric to be arbitrary? Can we just set g_{ab}= g_{ab}(e,f,g,h) where e, f, g and h are arbitrary variables...and not give an explicit form?
 

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