View source for Cograph

''component reducible graph''

An unoriented [[graph]] obtained from the single-vertex graph by the operations of disjoint union and complementation.  They are characterised by having no [[induced subgraph]] $P_4$, the path of length $4$.

They are the [[comparability graph]]s of [[series-parallel order]]s.

==References==
* Andreas Brandstädt, Van Bang Le; Jeremy P. Spinrad, "Graph classes: a survey". SIAM Monographs on Discrete Mathematics and Applications '''3'''. Society for Industrial and Applied Mathematics (1999) ISBN 978-0-898714-32-6 {{ZBL|0919.05001}}
* Rival, Ivan (ed.) ''Graphs and order. The role of graphs in the theory of ordered sets and its applications'' Reidel (1985) {{ZBL|0549.00002}}