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Published online by Cambridge University Press: 30 September 2008
We report on the systematic listing of polynomial relationsamong the algebraic invariants of a Riemann tensor. We constructall such relations for the 3 × 1029 invariants with upto seven Riemann tensors, and provide the computer algebra systemInvar (both for Mathematica and Maple)which uses them to maximally simplify any invariant within seconds.We also report work in progress to extend Invarand its database to handle all differential Riemann invariants upto 12 derivatives of the metric.