Velluscinum: A Middleware for Using Digital Assets in Multi-Agent Systems Nilson M. Lazarin 1,2 , Igor M. Coelho 1 , Carlos E. Pantoja 1,2 , and Jos´e Viterbo 1 1 Institute of Computing - Fluminense Federal University (UFF), Niter´ oi - RJ, Brazil 2 Federal Center for Technological Education Celso Suckow da Fonseca (Cefet/RJ), Rio de Janeiro - RJ, Brazil {nilson.lazarin,carlos.pantoja}@cefet-rj.br, {imcoelho,viterbo}@ic.uff.br Abstract. Distributed Ledger Technologies (DLT) characteristics can contribute to several domains, such as Multi-agent Systems (MAS), fa- cilitating the agreement between agents, managing trust relationships, and distributed scenarios. Some contributions to this integration are in the theoretical stage, and the few existing practical contributions have limitations and low performance. This work presents a MAS approach that can use digital assets as a factor of agreement in the relationship between cognitive agents using the Belief-Desire-Intention model. To val- idate the proposed methodology, we present the middleware Velluscinum that offers new internal actions to agents. The middleware was tested by adapting the Building-a-House classic example to cryptocurrency and agreements mediated by a distributed ledger. Keywords: Middleware · Multi-agents · Digital Ledger Technology. 1 Introduction Multi-agent Systems (MAS) are systems composed of multiple agents, which can be cognitive, through the use of the Belief-Desire-Intention (BDI) [4] model that enables the programming of mental attitudes like beliefs, desires, and intentions. These agents are called cognitive since they have a reasoning cycle capable of analyzing the information perceived in the environment in which they are in- serted, the knowledge acquired through communication with other agents, and making self-conclusions. These agents can interact or compete to resolve a task; in this relationship, conflicts and uncertainty can occur, so it is essential to pro- vide mechanisms for all agents to cooperate by guaranteeing reliability in the acquired information and used resources [23, 25]. Distributed Ledger Technologies (DLT) technologies have applications far beyond the financial sector, and their characteristics of decentralization, security, trust, and low cost of operation have a great capacity to contribute in various domains [9]. They are classified as permissionless or permissioned: in the first case, the access is unrestricted, the members can join and leave the network at any time, and finally, each node has a read-only copy of the data; the second case