Notes on the complexity of coverings for Kronecker powers of symmetric matrices

In the present note, we study a new method of constructing efficient coverings for Kronecker powers of matrices, recently proposed by J. Alman, Y. Guan, A. Padaki [arXiv, 2022]. We provide an alternative proof for the case of symmetric matrices in a stronger form. As a consequence, the previously known upper bound on the depth-2 additive complexity of the boolean $N\times N$ Kneser-Sierpinski matrices is improved to $O(N^{1.251})$.