Refinement-based verification of sequential implementations of Stateflow charts

Simulink/Stateflow charts are widely used in industry for the specification of control systems, which are often safety-critical. This suggests a need for a formal treatment of such models. In previous work, we have proposed a technique for automatic generation of formal models of Stateflow blocks to support refinement-based reasoning. In this article, we present a refinement strategy that supports the verification of automatically generated sequential C implementations of Stateflow charts. In particular, we discuss how this strategy can be specialised to take advantage of architectural features in order to allow a higher level of automation.Comment: In Proceedings Refine 2011, arXiv:1106.348

Deep Inelastic Scattering at HERA

Results from the H1 and ZEUS experiments at HERA on deep inelastic scattering are reviewed. The data lead to a consistent picture of a steep rise in the F_2 structure function and in the gluon density within the proton. Important new information on the partonic structure of diffraction is emerging from H1 and ZEUS. The space-like region in which the weak and electromagnetic interactions become of equal strength is being explored for the first time. A possible excess of events at high x and Q^2 compared to the expectations of the Standard Model has been observed in both experiments.Comment: 80 pages, 42 figure