Recent content by jojoo

  1. J

    Graduate Foliation, fibration, fiber bundle?

    what's the difference among those three objects? Any body can give me some examples? Thanks
  2. J

    Graduate How to Prove contracted Bianchi Identity

    Yes, I know that. But \nabla_{\partial_j}R_{ilkm}=(\nabla_{\partial_j}R)(\partial_i,\partial_l,\partial_k,\partial_m) How can the contraction really happen?(since \nabla_a g_{bc}=0 means (\nabla_a g)(\partial_b,\partial_c)=0) Would you like to give me more detail? Thank you!
  3. J

    Graduate How to Prove contracted Bianchi Identity

    How to prove g^{im} \nabla_{\partial_j}R_{ilkm}=\nabla_{\partial_j}R_{lk}. of cause g^{im}R_{ilkm}=R_{lk}, but I don't know how the contraction can pass through the covariant derivative?