@techreport{TR-IC-01-12,
number = {IC-01-12},
author = {F. Larrión and C. P. de Mello and V. Neumann-Lara and A. Morgana and M. A. Pizaña},
title = {The Clique Operator on Cographs and Serial Graphs},
month = {October},
year = {2001},
institution = {Institute of Computing, University of Campinas},
note = {In English, 12 pages.
\par\selectlanguage{english}\textbf{Abstract}
The {\bf clique graph} of a graph $G$ is the intersection graph $K(G)$ of
the (maximal) cliques of $G$. The iterated clique graphs $K^{n}(G)$ are
defined by $K^{0}(G)=G$ and $K^{i}(G)=K(K^{i-1}(G))$, where $i>0$ and $K$ is the
clique operator. A {\bf cograph} is a graph with no induced subgraph
isomorphic to $P_{4}$. In this article we describe the $K$-behaviour of
cographs and give some partial results for the larger class of serial
(i.e.~complement-disconnected) graphs.
}
}