Provenance techniques aim to increase the reliability of human judgments about data by making its origin and derivation process explicit. Originally motivated by the needs of scientific databases and scientific computation, provenance has also become a major issue for business and government data on the Web. However, so far provenance has been studied only in relatively restrictive settings: typically, for data stored in databases or scientific workflow systems, and processed by query or workflow languages of limited expressiveness. Long-term provenance solutions require an understanding of provenance in other settings, particularly the general-purpose programming or scripting languages that are used to glue different components such as databases, Web services and workflows together. Moreover, what is required is not only an account of mechanisms for recording provenance, but also a theory of what it means for provenance information to explain or justify a computation. In this paper, we begin to outline a such a theory of self-explaining computation. We introduce a model of provenance for a simple imperative language based on operational derivations and explore its properties.
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