Question on tensor notation in group theory

  1. in the appendix on Group Theory in Zee's book there is a discussion of commutations for SO(3)

    two questions

    - does [[itex]J^{ij},J^{lk}] = J^{ij}*J^{lk}-J^{lk}*J^{ij}[/itex]?

    and there is an expression in the appendix that the commutator equals i([itex]\delta^{ik}J^{jl} ...[/itex]

    i don't understand the why you are multiplying the matrix by the kronecker delta with different upstairs indexes, is not it simply an identity?
     
    Last edited: Apr 10, 2012
  2. jcsd
  3. bumping this - this apparantly is some notation I don't understand, the Wiki entry on Special Unitary groups has this as well

    [​IMG]

    I don't get the significance of the kronecker deltas with the different indexes
     
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