in the appendix on Group Theory in Zee's book there is a discussion of commutations for SO(3)(adsbygoogle = window.adsbygoogle || []).push({});

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?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Question on tensor notation in group theory

**Physics Forums | Science Articles, Homework Help, Discussion**