Dear colleague, We are organizing the Cluster on Network Optimization in the ALIO-INFORMS 2010 Joint International Meeting, to be held in Buenos Aires on June 6-9, 2010 (see http://meetings.informs.org/BuenosAires2010/). We would like to invite you to propose and chair a session with three (or four) papers, or alternaively, to submit an abstract (with no more than 500 characters) to be included in a session of the cluster. Let us know by the end of November. In case of accepting out invitation, further details will be sent to you on how to subnit the session or the abstract. With best regards, Bernard Fortz  (bernard.fortz@ulb.ac.be) Luis Gouveia (legouveia@fc.ul.pt)