Science

[ {\sum\limits_{{k = 1}}^{{n_{b} }} {e_{{i,j}}^{{(k)}} } } \right] [a\right] [ {\sum\limits_{{k = 1}}^{{n_{b} }} {e_{{i,j}}^{{(k)}} e_{{l,m}}^{{(k)}} } } \right]…