This paper deals with edge-clique graphs and with the lambda-coloring problem when restricted to this class. A characterization of edge-clique graphs of out-erplanar graphs is given; a complete description of edge-clique graphs of threshold graphs is presented and a linear time algorithm for lambda-coloring the edge-clique graph of a threshold graph is provided. A survey on the lambda-coloring problem, when restricted to edge-clique graphs, is reported.
edge-clique graphs; lambda-coloring; out-erplanar graphs; threshold graphs
