Department of Computer, Control and Management Engineering

The use of Digital Twins is key in Industry 4.0, in the Industrial Internet of Things, engineering, and manufacturing business space. For this reason, they are becoming of particular interest for different fields in Artificial Intelligence (AI) and Computer Science (CS). In this work, we focus on the orchestration of Digital Twins. We manage this orchestration using Markov Decision Processes (MDP), given a specification of the behaviour of the target service, to build a controller, known as an orchestrator, that uses existing stochastic services to satisfy the requirements of the target service. The solution to this MDP induces an orchestrator that coincides with the exact solution if a composition exists. Otherwise, it provides an approximate solution that maximizes the expected discounted sum of values of user requests that can be serviced. We formalize stochastic service composition and we present a proof-ofconcept implementation, and we discuss a case study in an Industry 4.0 scenario.