“…In this perspective, Multi Robot systems are an obvious choice for all those applications which implicitly take benefit of redundancy; i.e., applications in which, even in absence of a coordination strategy, having more robots working in parallel improves the system's fault tolerance, reduces the time required to execute tasks, guarantees a higher service availability and a quicker response to user requests. There are many cases for which this holds: autonomous cleaning (Jung & Zelinski, 2000;Kurazume et al, 2000); tour guiding in museums, art-galleries, or exhibitions (Siegwart et al, 2003); surveillance and patrolling (Rybski et al, 2002;Vidal et al, 2002), rescue in large scale disaster such as fires, floods, earthquakes (Bahadori et al, 2005); landmine detection (Acar et al, 2003); autonomous exploration and mapping, possibly with the additional constraint of retrieving samples or objects of interests (Rekleitis et al, 2000;Burgard et al, 2005). All the previous applications share some common characteristics: they require the execution of a set of loosely coupled tasks more or less comparable to "coverage", i.e., the problem of visiting the largest number of locations in a given area (Fontan & Matarić, 1996;Choset, 2001), and "foraging", i.e., the problem of finding objects or persons of interest ("food", in the metaphor) and returning them to a specified location (Arkin, 1992;Drgoul & Ferber, 1993).…”