O. Deux et al. The Story of O2. IEEE Transaction on Knowledge and Date Engineering, 2(1), March 1990.  Home/Search   Document Not in Database   Summary   Related Articles

....the concepts found in object oriented models and systems. The Data Model There are about as many object oriented data models as there are projects working on the subject. However, most of these models support the features proposed in [3] The model we consider here is close to the O 2 data model [11] and is general enough so that many different ones can be mapped on it. The model has classes and concrete types. Each class has a name, defines a structure and a behaviour. Classes obey the inheritance principle, they may have an extent, i.e. the set of all their instances. Their instances are ....

....between two classes. For instance, the attribute country in class Capital can be defined by the DBA as being the inverse of attribute capital in class Country . Most of the object oriented systems maintain class extents even if they are not always accessible to the programmers (e.g. in O 2 [11]) The extent of a class is the set containing all its instances. We have seen in the introduction, and we will come back to it in a more detailed manner in the next sections, that extents could be used to transform pointer chasing operations into algebraic operations. As such, extents are useful ....

O. Deux et al. The Story of O2. IEEE Transaction on Knowledge and Date Engineering, 2(1), March 1990.

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