Ant Colony Optimization and Swarm Intelligence: 4th International Workshop, ANTS 2004, Brussels, Belgium, September 5-8, 2004, Proceeding

1 With its fourth edition, the ANTS series of workshops has changed its name. Theoriginal ANTS FromAntColoniestoArti?cialAnts:InternationalWo- shop on Ant Algorithms has become ANTS International Workshop on Ant Colony Optimization and Swarm Intelligence . This change is mainly due to the following reasons. First, the term ant algorithms was slower in spreading in the research community than the term swarm intelligence , while at the sametime research inso-calledswarm robotics wasthesubjectofincreasingactivity:itwastherefore an obvious choice to substitute the term ant algorithms with the more accepted and used term swarm intelligence. Second, although swarm intelligence research has undoubtedly produced a 2 number of interesting and promising research directions , we think it is fair to say that its most successful strand is the one known as ant colony optimi- tion .Ant colony optimization, ?rst introducedin the early1990sasa noveltool fortheapproximatesolutionofdiscreteoptimizationproblems,hasrecentlyseen an explosion in the number of its applications, both to academic and real-world problems, and is currently being extended to the realm of continuous optimi- tion (a few papers on this subject being published in these proceedings). It is therefore a reasonable choice to have the term ant colony optimization as part of the workshop name.