In ontology development, modularity has received great attention in the past years; see, e.g., th... more In ontology development, modularity has received great attention in the past years; see, e.g., the LNCS monograph [27]. The non-standard reasoning tasks of extracting modules and of decomposing an ontology into modules have manifold applications in ontology reuse, versioning, debugging, and comprehension, as well as collaborative ontology development and automated reasoning optimization. When extracting a single module from a TBox T , that is, a subset M that can be used as a proxy for T , it is crucial for all these scenarios that M encapsulates the knowledge from T about a certain topic, which is usually taken to be a set of terms, the seed signature Σ. This encapsulation is typically captured via the notion of Σ-inseparability [17,2,3,15], which generalizes that of a conservative extension [4,20,13]. However, depending on the application, the widely adopted requirement thatM be Σ-inseparable from T is not always sufficient. For example, when importing M in place of T into an exte...
Many large ontologies are developed modularly, often using import statements, which are supported... more Many large ontologies are developed modularly, often using import statements, which are supported by the OWL standard. However, import statements do not provide logical guarantees such as local completeness, which is an established quality criterion for ontology modules: an ontology is locally complete if it uses terms from imported ontologies without changing the knowledge reused from them. To measure the extent to which ontologies separated by import statements are logically modular, we present four new quantitative logic-based metrics: two are strongly related to local completeness and based on module extraction, using some established module notion as a reference; the other two exploit the dependency relation of the atomic decomposition. We formally study the relationship between the measures and evaluate them on a set of ontologies.
Proceedings of the Eighteenth International Conference on Principles of Knowledge Representation and Reasoning, 2021
Various properties of ontology modules have been studied, such as coverage, self-containment, dep... more Various properties of ontology modules have been studied, such as coverage, self-containment, depletingness, monotonicity, preservation of justifications. These properties are important from a theoretical and practical point of view because they ensure, e.g., that modules have meaningful interfaces, can be used for ontology debugging, or are suitable for computing a meaningful modular structure of an ontology, such as via atomic decomposition (AD). Given one of the many existing module notions, it is not always obvious whether it satisfies a given property, particularly when the module extraction procedure is based on normalization. We investigate several module properties from an abstract point of view with an emphasis on properties relevant for AD. We examine their interrelations, their relation with iterated module extraction, their preservation in normalization-based module notions, and the adjustment of the latter to the requirements of AD. As a case study, we apply our results...
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Papers by Robin Nolte