Co-Fields In Other Scenarios. The problem of coordinating the movements of a group agents has lots of in- teresting applications in several scenarios. Let us consider the exemplary per- vasive computing problem of tourists visiting a museum assisted by personal digital assistants. Specifically, we can focus on how tourists can be supported in coordinating their movements with other, possible unknown, tourists. Such co- ordination activities may include scheduling attendance at specific exhibitions, having a group of students split in the museum according to teacher-specific laws, helping a tourist to avoid crowd or queues, letting a group of tourist to meet together at a suitable location, and even helping to escape accordingly to specific emergency evacuation plans. To apply the Co-Fields model to this scenario, we need a computer infrastruc- ture suitable in supporting fields propagation across the museum. Specifically, we can suppose that the museum is provided with an adequate embedded com- puter network. In particular, embedded in the museum walls (either associated to each artistic items or to each museum room), there will be a network of com- puter hosts, each capable of communicating with each other and with the mobile devices located in its proximity via the use of a short-range wireless link. The number of the embedded hosts and the topology of the network may depend on the museum, but the basic requirement is that the network topology mimics the topology of the museum plan (i.e. no network links between physical barriers, like walls). On each host there will be a middleware providing basic support for data storing (to store field values) and communication mechanisms (to prop- agate fields) [13]. Moreover, we can suppose that tourists are provided with a software agent running on some wireless handheld device, like a palm computer or a cellular phone, in charge of giving her/him suggestions on where to move. Devices connect to nearby embedded hosts (to this end some kind of lo- calization mechanism has to be enforced [2]). They can inject fields across the network and read field values in the neighborhood to enforce field-based coor- dination (e.g. move to the room where the gradient of a field goes downhill). With this regard, it is worth noting that the critical assumption made about the museum network topology is about not having people stumbling at walls while following gradients. More details on this Co-Fields application can be found in [12]. The above scenario and the ...
