In this paper we report about an approach to establish safety properties of cooperating systems in polynomial time, the state space of which can be exponentially large in the number of cooperating subsystems. It consists of constructing a family of so-called inducers of a system and the reduction of these by an operator we call Edge-Match. Furthermore, we draw a connection between our approach and the theory of relational databases. Aside from pointing out an interesting connection between these fields we use this connection to apply results from the theory of relational databases to our approach. (C) 2014 Elsevier B.V. All rights reserved.