The understanding of Semantic Web documents is built upon ontologies that define concepts and relationships of data. Hence, the correctness of ontologies is vital. Ontology reasoners such as RACER and FaCT have been developed to reason ontologies with a high degree of automation. However, complex ontology-related properties may not be expressible within the current web ontology languages, consequently they may not be checkable by RACER and FaCT. We propose to use the software engineering techniques and tools, i.e., Z/EVES and Alloy Analyzer, to complement the ontology tools for checking Semantic Web documents. In this approach, Z/EVES is first applied to remove trivial syntax and type errors of the ontologies. Next, RACER is used to identify any ontological inconsistencies, whose origins can be traced by Alloy Analyzer. Finally Z/EVES is used again to express complex ontology-related properties and reveal errors beyond the modeling capabilities of the current web ontology languages. We have successfully applied this approach to checking a set of military plan ontologies.

The development of computer networks, especially the internet, has largely facilitated the communications among software developers and it resulted a thriving of open source software systems (OSS). As more and more open source software systems are deployed by individuals and enterprises, it is vital to study such systems separately from traditional software systems since their development and maintenance processes are fairly different. In this paper, we investigate a type of behaviors of software maintenance of open source software systems and propose an approach that is based on NHPP with Rayleigh function to model the maintenance activities. Using the proposed model, the maintenance events could be estimated with high confidence and this will certainly assistant software maintenance planning. A numerical example using from the data from Apache project is shown to illustrate the application of our model.