Semantic Web-Based Information Systems: State-of-the-Art ...

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explicit provides important support for the conceptual calibration activities 15 that
are necessary in order to achieve semantic collaboration. The ULM verbal-to-visual
contextual representation technique has a crucial advantage compared to similar
techniques, such as concept maps (Concept Maps, n.d.; Novak, n.d.) or topic maps
(Topicmaps, n.d.), which have to rely on purely verbal semantics in order to convey
their conceptual relationships.
In order to be able to correctly interpret the context maps of this chapter, we will
give a brief description of some of the extra notation introduced in ULM compared
to UML. 16
As discussed earlier, UML represents the example-type (instance-type) relation
on the instance itself, as shown in the left part of Figure 3, which shows that the
depicted concept is an (unnamed) instance of type car. The right part of the figure
shows the same relation represented in ULM. The dashed arrow (with a small filled
head) represents the classification/instantiation and is pronounced is a when read
Figure 3. UML: A car is a(n instance of type) car
Figure 4. A car is a car is a concept is a concept is a ...
Figure 5. Traditional OO: Car is a vehicle. ULM: Car kind of vehicle
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