The diagonal elements are the sums of the resistances in the meshes, and the off-diagonal element are the negatives of the resistances common to the meshes corresponding to the row and column of the determinant. That is, r2 in row 1, column 2 or in row 2, column 1 is the negative of the resistance common to meshes 1 and 2, etc. Thus the determinant is symmetric about its diagonal. This symmetry is not preserved, of course, if there are dependent sources present.