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HallsofIvy
#4
Mar30-10, 06:38 AM
Math
Emeritus
Sci Advisor
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PF Gold
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Christoffel symbols

The ordinary derivative of a tensor is NOT a tensor. In order to make it one, the "covariant derivative", you have to subtract off the Christoffel symbols- or, to put it another way, the Chrisoffel symbols are the covariant derivative minus the ordinary derivative.