The matrix capacity of a tensor

In 1990, D. Coppersmith and S. Winograd published an estimate of the amount of arithmetic operations necessary for the multiplication of square matrices $n\times n$, which equals $O(n^{2.3755})$. In this article, we make a systematization of the theoretical instruments that were used by D. Coppersmith and S. Winograd for their estimate. The improved estimate $O(n^{2.373})$ is one of the results of this systematization.