Apart from the aforementioned practical platforms, which are already in operation, there are several papers that propose different solutions for carpooling. Some of them are centred on route optimization, and others focus on cooperation enforcement or passenger matching, and others are centred in multi-agent platforms. First, the work  shows an integrated system with an optimization module, which applies heuristic methods to solve the organization of the routing problem in carpooling services by using different technologies such as Web, Geographic Information System (GIS) and Short Message Service (SMS). Second, the paper  defines a push service to promote carpooling through instant processing. The paper  presents a carpooling architecture that uses a credit mechanism to encourage cooperation among users, by defining a business model where such a credit can be used in parking facilities and can be bought with real money. A more recent work is , where an algorithm to encourage carpooling is proposed based on assigning priority to users with positive feedback through a fuzzy logic scheme. Thirdly, an automatic service to match commuting trips is presented in . In addition, passenger matching is the topic of the paper , where a system is proposed to help users in choosing a transport solution according to its ecological footprint, matching their needs, preferences, and actual location. Finally, another interesting proposal is , based on a multi-agent platform that focuses on security services that allow the mutual authentication of the users and of the application components with the system.