A curvature operator, that is, a
linear map R : Λ2V → Λ2V , has bounded rank 2r if it maps simple bivectors into
bivectors of rank ≦ 2r. It is shown here that this condition is equivalent to the
following:
for all x1,⋯,xr+1, y1,⋯,yr+1 in V , with the sum taken over all permutations
(i1,⋯,ir+1) of (1,2,3,⋯,r + 1). An application to Riemannian geometry is
given.
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