In differential geometry, Vermeil's theorem essentially states that the scalar curvature is the only (non-trivial) absolute invariant among those of prescribed type suitable for Albert Einstein’s theory of General Relativity. The theorem was proved by the German mathematician Hermann Vermeil in 1917.
Standard version of the theorem The theorem states that the Ricci scalar Let us recall that Ricci scalar is linear in the second derivatives of the metric tensor , quadratic in the first derivatives and contains the inverse matrix which is a rational function of the components . is the only scalar invariant (or absolute invariant) linear in the second derivatives of the metric tensor .
See also Scalar curvature Differential invariant Einstein–Hilbert action Lovelock's theorem
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