# Mobility, Citizens, Innovation and Technology in Digital and Smart Cities
## 2 The Search for an Optimized Urban Transportation Ecosystem
### Smart Routing Problems: Multi-Objective Optimization  
Vehicle Routing Problems (VRP) [31] cover a wide variety of problems faced by modern society, both in the industry and public sector. From a simple route apparently taken by a postman [32] in order to deliver packages to a set of customers, humans have been facing complex decision-making scenarios in which computers' assistance has been shown to be crucial. These challenges are now being solved without users realizing how it indeed happens. In this sense, we pinpoint the open opportunities for innovative applications that should carefully consider the users' profiles, wishes and desired goals. Furthermore, due to the current advances of many-objective visualization tools [33; 34], we expect that data visualization on complex problems will start to turn into common tools used by the industry and decision makers.  
Recently, an optimal trip system was claimed by [PERSON] et al. [35]. At this point, we highlight the discussion about what is actually an optimal trip in the context of a multicultural SC? While some will surely enjoy specific paths (with particular amount of light, temperature, wind, etc.), others will opt for the fastest or the less noisy. In addition, the specific types of vehicles and mobility systems that each person uses is another point to be added to this multi-objective scenario [36; 37]. Furthermore, when public transportation systems are considered, cost and speed is another trade-off handled when citizens use transport integration [38]. The resolution of problems in the scope of green logistics is under discussion not only by the academia [39; 40; 41; 42] but also by the industry [43; 44], which basically involve different models for calculating the cost of the routes, involving other components in the objective function equation, such as carbon emissions [45; 46]. Discussions under the scope of autonomous also involve batteries and fuel cell based equipment [47]. In this sense, there is a trend in researching more sustainable transports connected with the achievement of higher profits [48], which are concepts that should match for the achievement of a widespread adoption by the industry.  
Let us consider an undirected graph \(G=(V,E)\), where \(V=\{v_{1},v_{2},\cdots,v_{n}\}\) and \(E=\{(i,j)\mid v_{i},v_{j}\in V,i<j\}\) represent, respectively, the vertices and edges of a given graph \(G\). [PERSON] and [PERSON] [49] designed an Adaptive Local Search Procedure for tackling a travelling salesman problems in which the rented car could be returned or not at the nodes from a graph \(G\). In this sense, the graph could contain dynamic points in which the users might spontaneously decide where to deliver the vehicle regarding a set of stochastic aspects. It is noteworthy that this problem can be adapted for dealing with several rented cars and car sharing systems on urban scenarios. [PERSON] et al. [50] considered routes that could be optimized according to different operating modes, such as: pure combustion mode, pure electric mode, charging mode (in which the battery is charged while driving with the combustion engine) and a boost mode (in which combustion and electric engines are combined for the drive). However, other points are still open to be considered, such as modes in which the vehicle would charge from: breaks, solar radiation or even rapid winds streams. The study of [PERSON] et al. [23] also provides an idea on how routing can be considered under many different points of view, defining routes in terms of \"smellwalks\", in a study where participants followed different smellscapes and asked to record their experiences.