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math214:hw13 [2020/04/26 23:58]
pzhou
math214:hw13 [2020/04/27 10:18]
pzhou
Line 9: Line 9:
 $$ a_{ij}(t) = \la R(\dot \gamma(t), e_i(t)) \dot\gamma(t), e_j(t) \ra $$ $$ a_{ij}(t) = \la R(\dot \gamma(t), e_i(t)) \dot\gamma(t), e_j(t) \ra $$
 Prove that the Jacobi equations can be written as  Prove that the Jacobi equations can be written as 
-$$ \ddot f_i(t) + \sum_{j} a_{ij}(t) f_j(t) = 0, \quad \forall i=1,\cdots, n $$+$$ \ddot f_j(t) + \sum_{if_i(t) a_{ij}(t)  = 0, \quad \forall j=1,\cdots, n $$
  
 2. (2pt) Jacobi equation in constant sectional curvature. Let $M$ be a manifold with constant sectional curvature $K$ (recall the definition of sectional curvature on page 168 in [Ni]). Let $\gamma$ be a normalized geodesic, i.e $|\dot \gamma(t)|=1$. Show that the Jacobi equation in a parallel orthonormal basis (as in problem 1) become 2. (2pt) Jacobi equation in constant sectional curvature. Let $M$ be a manifold with constant sectional curvature $K$ (recall the definition of sectional curvature on page 168 in [Ni]). Let $\gamma$ be a normalized geodesic, i.e $|\dot \gamma(t)|=1$. Show that the Jacobi equation in a parallel orthonormal basis (as in problem 1) become
math214/hw13.txt · Last modified: 2020/04/29 10:34 by pzhou