“…There have been a number of O n 4 , O n 3 , O nm , and O n 2 algorithms for finding modular decomposition, such as Buer and Möhring [1], Ehrenfeucht et al [8], Golumbic [11], Habib and Maurer [14], McConnell [17], Muller and Spinrad [24], Steiner [26], some of them for special cases or generalizations of the problem. The cotree decomposition of cographs and the series-parallel decomposition of series-parallel partial orders are special cases on graphs and digraphs, respectively, for which linear-time solutions have been given (see Corneil et al [3]; Valdes et al [28]).…”