Curvature tensors whose Jacobi or Szabo operator is nilpotent on null vectors

Peter Gilkey, Iva Stavrov

英文摘要：

We show that any $k$ Osserman Lorentzian algebraic curvature tensor has constant sectional curvature and give an elementary proof that any local 2 point homogeneous Lorentzian manifold has constant sectional curvature. We also show that a Szabó Lorentzian covariant derivative algebraic curvature tensor vanishes.

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