
A Riemannian space \(V_ n\) is said to admit an almost geodesic mapping of type \(\pi_ 2\) onto \(\bar V_ n\) (N. S. Sinyukov), if there exist tensor fields \(\phi_ i,\psi_ i,\sigma_ i,\nu_ i\) and \(U^ k_ i\) satisfying the conditions: \({\bar\Gamma }{}^ h_{ij}=\Gamma^ k_{ij}+\phi_{(i}\delta^ k_{j)}+\psi_{(i}U^ k_{j)}\), \(U^ k_{(i,j)}+\psi_{(i}U^ n_{j)}U^ h_ r= \delta_{(i}\delta^ k_{j)}+\nu_{(i}U^ k_{j)}\), where the notations are chosen in the usual manner. This mapping is said to be reduced (V. S. Sobchuk), if the following relations are satisfied \(U^ r_ iU^ h_ r=\epsilon\delta^ h_ i\); \(\epsilon =\pm 1\); \(\psi_{i,j}=U_{ij}+\psi_{(i}U^ r_{j)}\phi_ r\), where \(\phi_ i=\phi_{,i},\psi_ i=\psi_{,i}\) and \(U_{ij}=g_{ir}U^ r_ j\). The author proves the following theorem: Let \(V_ n (n>2)\) admit a reduced almost geodesic mapping onto a semisymmetric Riemannian space \(\bar V_ n\). Suppose, moreover, that the function a-\(n\epsilon\) does not vanish identically, where \(a=a_{ij}g^{ij}\) and \(a_{ij}=\phi_{i,j}-\phi_ i\phi_ j-\phi_ rU^ r_{(i}\psi_{j)}+\epsilon\psi_ i\psi_ j\), then \(\bar V_ n\) is of constant curvature and \(V_ n\) is locally symmetric. This theorem generalizes results of V. S. Sobchuk when \(V_ n\) is locally symmetric.
Local Riemannian geometry, semisymmetric Riemannian space, reduced almost geodesic mapping, almost geodesic mapping, constant curvature
Local Riemannian geometry, semisymmetric Riemannian space, reduced almost geodesic mapping, almost geodesic mapping, constant curvature
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