Applying PSP to MM ...
The idea of flooding for MM generalizes ...
region IK = [1..n, 1,1..n];
KJ = [ 1,1..n,1..n];
IJ = [1..n,1..n, 1];
IJK = [1..n,1..n,1..n];
[IK] A2 := <##[Index1,Index3,Index2] A;
[KJ] B2 := <##[Index3,Index2,Index1] B;
[IJ] C := +<<[IJK] ((>>[IK]A2)*(>>[KJ]B2));