Don t know if the commutation relations should be stated at the outset They are a prerequisite for the article i e really belong in either Lorentz group or Lorentz lie algebra if it existed Also they aren t used exlicitly unless we beef out completely I m mainly thinking of preservation of space here A couple of stylistic issues I don t like visible references They take up space and if given they should I m o be to a really reputable source The colon equation style may exist in some sense but blending in that style with what is standard standard used in the rest of the aricle is hurting the eye a bit and is a stylistic nono I edited your edit regarding the four or two or whatever indices in an equation I feel that a full explanation of the indices belongs to the Kronecker product article which is I think linked