**2.1.6 Evaluation of telecommunications service domain ontology**

Ontology evaluation is an important issue that must be addressed if TSDO are to be widely adopted in the semantic related telecommunications applications. Ontology can be

Telecommunications Service Domain Ontology:

integrate these two ontologies into a new ontology.

Fig. 8. Ontology integration based on the equivalent mapping.

Fig. 9. Ontology integration based on the subsumption relationship.

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maintenance. Therefore, sometimes, it needs to integrate several existent ontologies to address the reuse of different ontology knowledge. To implement the different ontology integration, the relationships among different ontologies should be analyzed. As the distributed feature and openness of WWW, knowledge ontologies maybe have the direct or indirect semantic relationships. For example, two ontologies maybe involve some same or similar concepts. The main relationships consist of two kinds: one is the repeat of terminologies definition. Some terminologies of this ontology might be equivalent to those defined in that ontology. It consists of the class equivalent and the property equivalent. For this equivalent relationship, we can use equivalent ontology mapping method to resolve as shown in Figure 8. The other is the subsumption of terminologies definition. It means that some terminologies of one ontology might subsume the semantic scope of those terminologies defined in other ontology. It also involves the class subsumption and property subsumption. For example, Figure 9 shows two independent ontologies: ontology 1 and ontology 2. In fact, the concept "Netowrk" of ontology 1 subsumes the concept "Internet" of ontology 2 in the semantic scope. Therefore, we can use the subsumption relationship to

evaluated against many criteria: its coverage of a particular domain and the richness, complexity and granularity of that coverage; the specific use cases, scenarios, requirements, applications, and data sources it was developed to address; and formal properties such as the consistency and completeness of the ontology. We can test and validate whether the domain ontology satisfy the requirement or not. If yes, these ontologies will be added to the ontology repository; if no, we have to return back to previous steps to make some revisions until the requirement is satisfied.

In the specific use process, we often can find some existing shortcomings of domain ontology. The utilization of domain ontology to formally describe the concrete application scenario is a very effective evaluation approach. For example, when we defined the TSDO, we use network, service role and service category sub-ontologies to describe the network carrier resource (see Figure 7). We found that the operating scope of network carrier is an important characteristic. But the concept "NetworkOperator" of service role sub-ontology lacks this property. Actually, some carriers can provide services through out nation; however, some carriers can only provide services in a specific province or region. Therefore, the property "CoverageScope" should be added to the concept "NetworkOperator" of service role sub-ontology.


Fig. 7. Ontology description of china mobile communication operator.
