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We present the language CRStL (Control Rule Strategy Language, pronounce "crystal") to formulate mathematical reasoning techniques as proof strategies in the context of the proof assistant mega. The language is arranged in two levels, a query language to access mathematical knowledge maintained in development graphs, and a strategy language to annotate the results of these queries with further control information. The two-leveled structure of the language allows the specification of proof techniques in a declarative way. We present the syntax and semantics of CRStL and illustrate its use by examples.

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Industrial standards establish technical criteria for various engineering artifacts, materials, or services, with a view to ensuring their functionality, safety, and reliability. We develop a methodology and tools to systematically formalize such standards, in particular their domain specific calculation methods, in order to support the automatic verification of functional properties for concrete physical artifacts. We approach this problem in the setting of the Bremen heterogeneous tool set HETS, which allows for the integrated use of a wide range of generic and custom-made logics. Specifically, we (i) design a domain specific language for the formalization of industrial standards; (ii) formulate a semantics of this language in terms of a translation into the higher-order specification language HASCASL, and (iii) integrate computer algebra systems (CAS) with the HETS framework via a generic CAS-Interface in order to execute explicit and implicit calculations specified in the standard. This enables a wide variety of added-value services based on formal reasoning, including verification of parameterized designs and simplification of standards for particular configurations. We illustrate our approach using the European standard EN 1591, which concerns calculation methods for gasketed flange connections that assure the impermeability and mechanical strength of the flange-bolt-gasket system. Work performed as part of the project FormalSafe funded by the German Federal Ministry of Education and Research (FKZ 01IW07002).