A Kronecker delta is a compact notation that indicates the equivalent of a dot product in vector notations. In this usage, it takes the form of a Greek letter delta with two subscripts which indicate that the components are to be multiplied if the...

In mathematics, the Kronecker delta or Kronecker's delta, named after Leopold Kronecker (1823-1891), is a function of two variables, usually integers, which is 1 if they are equal, and 0 otherwise. So, for example, \delta_{12} =...