Curvature tensors in dimension four which do not belong to any curvature homogeneous space
Oldřich Kowalski, Friedbert Prüfer (1994)
Archivum Mathematicum
Similarity:
A six-parameter family is constructed of (algebraic) Riemannian curvature tensors in dimension four which do not belong to any curvature homogeneous space. Also a general method is given for a possible extension of this result.