be solved using a similar strategy (Möhring, 85). Cographs are the graphs that only have parallel or series nodes in their modular decomposition tree. The first polynomial algorithm to compute the modular decomposition tree of a graph was published in 1972 (James, Stanton & Cowan 1972) and now linear algorithms are available (McConnell & Spinrad 1999, Tedder et al. 2007, Cournier & Habib 1994). Generalizations Modular decomposition of directed graphs can be done in linear time . With a small number of simple exceptions, every graph with a nontrivial modular decomposition also has a skew partition . References External links A Perl implementation of a modular decomposition algorithm A Java implementation of a modular decomposition algorithm A Julia implementation of a modular decomposition algorithm Graph theory objects