We lift the problem of enumerative solution counting to quantified Boolean formulas (QBFs) at the second level. In contrast to the well-explored model counting problem for SAT (#SAT), where models are simply assignments to the Boolean variables of a formula, we are now dealing with tree (counter-)models reflecting the dependencies between the variables of the first and the second quantifier block. It turns out that enumerative counting on the second level does not give the complete model count. We present the - to the best of our knowledge - first approach of counting tree (counter-)models together with a counting tool that exploits state-of-the-art QBF technology. We provide several kinds of benchmarks for testing our implementation and illustrate in several case studies that solution counting provides valuable insights into QBF encodings.

Gridlink provides a communication infrastructure for the implementation of distributed control systems in Java. It is a completely decentralized solution where the communication partners dynamically form a cluster of known instances during execution. Gridlink uses a distributed event bus based on an asynchronous communication model. A typical Gridlink system is built from a set of modules that execute a distributed application and that communicate with each other by exchanging messages. We present a smart grid use case dealing with the detection and handling of voltage band violations in low voltage networks deployed in secondary substation nodes.