Using Trust and “Utility” for Group Formation in the Cloud of Things Giancarlo Fortino 1 , Lidia Fotia 2(B ) , Fabrizio Messina 3 , Domenico Rosaci 4 , and Giuseppe M. L. Sarn´ e 2 1 Department DIMES, University of Calabria, Rende, CS, Italy giancarlo.fortino@unical.it 2 DICEAM, University Mediterranea of Reggio Calabria, Reggio Calabria, Italy {lidia.fotia,sarne}@unirc.it 3 DMI, University of Catania, Catania, Italy messina@dmi.unict.it 4 DIIES, University Mediterranea of Reggio Calabria, Reggio Calabria, Italy domenico.rosaci@unirc.it Abstract. In this paper we consider a CoT (Cloud of Things) scenario where agents cooperate to perform complex tasks. Agents have to select reliable partners and, in some cases, they don’t have enough informa- tion about their peers. In order to support agents in their choice and to maximize the benefits during their cooperation, we combined several contributions. First of all, we designed a trust model which exploits the recommendations coming from the ego networks of the agents. Secondly, we propose to partition the agents in groups by exploiting trust rela- tionships to allow agents to interact with the most reliable partners. To this aim, we designed an algorithm named DAGA (Distributed Agent Grouping Algorithm) to form agent groups by exploiting available reli- ability and reputation and the results obtained in a simulated scenario confirmed its potential advantages. 1 Introduction Lately, the “Internet of Things” (IoT) and Cloud Computing (CC) converged to achieve the so called Cloud-of-Things [1, 28] (CoT). Also in nomadic contexts [2], CoT supports computational and storing requirements [5] of omnipresent and heterogeneous IoT devices. Furthermore, the association of IoT devices with software agents, working on their behalf on the Cloud [14, 15, 31], allows to take benefit from their social attitudes. In such a scenario, it is important that an agent, even in the case of unsuitable information, is able to make a good choice about its “partners” (i.e., agents). To this purpose, we propose of supporting agents to form groups of reliable recom- menders on the basis of some type of social relationships having place among the group members [6–8, 12]. In particular, we assumed that trust-based processes can potentially support agents in forming groups of reliable recommenders over a CoT context for improving IoT devices activities. c  Springer Nature Switzerland AG 2019 R. Montella et al. (Eds.): IDCS 2019, LNCS 11874, pp. 112–122, 2019. https://doi.org/10.1007/978-3-030-34914-1_11