In Einstein notation, the duplication on the i index implies the sum on i. The earlier is then denoted εijkεimn = δjmδkn − δjnδkm. but see that If your metric signature consists of an odd quantity of detrimental eigenvalues q, then the indication in the factors of the tensor differ https://rafaelmjfbw.blogadvize.com/33042570/levis-gacor-an-overview