Pilu Crescenzi Miriam Di Ianni Federico Greco Gianluca Rossi Paola Vocca Making Role Assignment Feasible: A Polynomial-Time Algorithm for Computing Ecological Colorings. 90-100 2008 WG http://dx.doi.org/10.1007/978-3-540-92248-3_9 conf/wg/2008 db/conf/wg/wg2008.html#CrescenziIGRV08