Constraint-logic object-oriented programming facilitates the integrated development of business software that occasionally solves constraint-logic problems or makes other use of structured search. So far, work in constraint-logic object-oriented programming has been limited to considering constraints that only involve logic variables of primitive types; in particular, boolean, integer, and floating-point numbers. However, the availability of object-oriented features calls for the option to use logic variables in lieu of objects as well. Therefore, support for reference-type logic variables (or free objects) is required. With the work at hand, we add support for free objects to a Java-based constraint-logic object-oriented language, Muli. Allowing free objects in statements and expressions results in novel interactions with objects at run time, for instance, non-deterministic execution of polymorphic method invocations (taking arbitrary class hierarchies into account) and non-deterministic type operations. At run time, this is supported by a dynamic type constraint that restricts the possible types of a free object at non-deterministic choices.

Indoor Localization Systems (ILS) are increasingly applied in various use cases, such as tracking the position and movement of staff or equipment within buildings. Creating and applying these systems requires decisions about measuring and transmitting signals, the algorithm transforming signals into position estimations as well as the representation displayed to the user. One approach gaining significance recently in this context are Mesh Networks. A Mesh Network enables single nodes to exchange information with other nodes directly and dynamically, increases the error-tolerance, and facilitates the setup by reducing installation overhead. This paper studies the applicability of Bluetooth Mesh Networking technology for ILS by means of an experimental setup. The quality of localization is evaluated depending on different inference approaches as well as the scalability of the Bluetooth Mesh Technology. As initial results show, ILS based on Bluetooth Mesh Networks provide similar results regarding the accuracy of localization compared to other underlying technologies, such as Wi-Fi mesh networks, and can be set up with lower effort and costs. However, the underlying Bluetooth technology limits the scalability of the mesh network, especially in case of permanent localization of nodes.