A characterization of Riemannian manifolds

Author(s):  
P. I. Petrov
Keyword(s):  
1993 ◽  
Vol 131 ◽  
pp. 127-133 ◽  
Author(s):  
Qing-Ming Cheng

Let Mn be an n-dimensional Riemannian manifold minimally immersed in the unit sphere Sn+p (1) of dimension n + p. When Mn is compact, Chern, do Carmo and Kobayashi [1] proved that if the square ‖h‖2 of length of the second fundamental form h in Mn is not more than , then either Mn is totallygeodesic, or Mn is the Veronese surface in S4 (1) or Mn is the Clifford torus .In this paper, we generalize the results due to Chern, do Carmo and Kobayashi [1] to complete Riemannian manifolds.


2007 ◽  
Vol 87 (1-2) ◽  
pp. 150-159
Author(s):  
Grozio Stanilov ◽  
Yulian Tsankov
Keyword(s):  

2009 ◽  
Vol 51 (2) ◽  
pp. 301-314 ◽  
Author(s):  
S. M. BUCKLEY ◽  
K. FALK ◽  
D. J. WRAITH

AbstractWe consider Ptolemy's inequality in a metric space setting. It is not hard to see that CAT(0) spaces satisfy this inequality. Although the converse is not true in full generality, we show that if our Ptolemaic space is either a Riemannian or Finsler manifold, then it must also be CAT(0). Ptolemy's inequality is closely related to inversions of metric spaces. We exploit this link to establish a new characterization of Euclidean space amongst all Riemannian manifolds.


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