The well known "SOR" method is obtained from a one-part splitting of the system matrix $A$, using one parameter $\omega$.
M. Sisler introduced a new method by using one parameter for the lower triangular matrix $L$. Later he combined the above two methods to get a two parametric method , , and .
D. Young considered yet another two parametric method. The two parameters weight the diagonal of a positive-definite and consistently ordered 2-cyclic matrix . Removing Young's hypothesis that both parameters are in the interval $(0,1]$, we generalized his theorem.
"A Generalization of Young's Theorem." Missouri J. Math. Sci. 4 (2) 76 - 87, Spring 1992. https://doi.org/10.35834/1992/0402076