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...evolution, only the current version of the schema is valid, and all data must be converted (in lazy or eager mode) in order to maintain the consistency of the database. In contrast, schema versioning =-=[105]-=- makes it possible to view the data under different versions of the schema. In SCM systems, versioning of the schema (and other meta data such as version rules) is rarely considered seriously. On the ...

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... trace of the changes that led from one version to another. 3.1 Ontology Versioning and Evolution is Change Management Database researchers distinguish between schema evolution and schema versioning (=-=Roddick 1995-=-). Schema evolution is the ability to change a schema of a populated database without loss of data (i.e., providing access to both old and new data through the new schema). Schema versioning is the ab...

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...akes ontology evolution a very complex operation that should be considered as both, an organizational and a technical process [25]. It requires a careful analysis of the types of the ontology changes =-=[24, 27]-=- that can trigger evolution as well as the environment in which the whole ontology evolution process is realized [28]. Although evolution over time is an essential requirement for useful ontologies [6...

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...ir structure when logs of changes are not available. The main thrust of research in database-schema versioning also uses the assumption that a record of changes between versions is readily available (=-=Roddick 1995-=-). Usually, researchers identify a canonical set of schema-change operations and consider effects of these operations on instance data as it migrates from one version to another (Banerjee et al. 1987)...

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... [14]. While there exist significant differences between schema evolution and ontology evolution, as elaborated in [13], particular aspects of schema evolution in databases are relevant for our work. =-=[16]-=- provides an excellent survey of the main issues concerned. A sound and complete axiomatic model for dynamic schema evolution in object-based systems is described in [15]. This is the first effort in ...

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...a description of the context in which the update is valid. In its simplest form, this might consist of the date when the change is valid in the real world, conform to valid date in temporal databases =-=[18] (in-=- this terminology, the “date” in the descriptive meta-data is called transaction date). More extensive descriptions of the scope, in various degrees of formality, are also possible. A well-designe...

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...e the problems sketched above into account are needed. There are other research areas that also consider change of information sources. Most closely related is the area of evolving database schemata (=-=Roddick, 1995-=-; Roddick et al., 2000), and especially evolving object oriented databases (Banerjee et al., 1987). Although from the surface this area look very similar ontology change, the scale and extent of the p...