Alexander Pretschner

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As the number of Internet users and the number of accessible Web pages grows, it is becoming increasingly difficult for users to find documents that are relevant to their particular needs. Users must either browse through a large hierarchy of concepts to find the information for which they are looking or submit a query to a publicly available search engine(More)
With the exponentially growing amount of information available on the Internet, the task of retrieving documents of interest has become increasingly difficult. Search engines usually return more than 1,500 results per query, yet out of the top twenty results, only one half turn out to be relevant to the user. One reason for this is that Web queries are in(More)
Among other domains, learning finite-state machines is important for obtaining a model of a system under development, so that powerful formal methods such as model checking can be applied. A prominent algorithm for learning such devices was developed by Angluin. We have implemented this algorithm in a straightforward way to gain further insights to(More)
We present the Obligation Specification Language (OSL), a policy language for distributed usage control. OSL supports the formalization of a wide range of usage control requirements. We also present translations between OSL and two rights expression languages (RELs) from the DRM area. These translations make it possible to use DRM mechanisms to enforce OSL(More)
Model-based testing relies on behavior models for the generation of model traces: input and expected output---test cases---for an implementation. We use the case study of an automotive network controller to assess different test suites in terms of error detection, model coverage, and implementation coverage. Some of these suites were generated automatically(More)
Model-based development relies on the use of explicit models to describe development activities and products. Explicit process and product models allow the definition and use of complex development steps that are correct by design, the generation of proof obligations for a given transformation, requirements tracing, and documentation of the process. We(More)