SPATIAL DATA MODELING: THE MODUL-R FORMALISM AND CASE TECHNOLOGY
Yvan Bédard, J.F. Pageau · 1992
abstraction and generalization . 5.5.1 The abstraction sub-module. It proposes two techniques: the use of five levels of abstraction based on the creation of themes and the use of different views (Figure 3j). The complexity of conceptual data model is managed with five levels of abstraction : summary, global, themes, detailed and integrated dictionary levels. These levels allow the presentation of the model with just a few details or with a lot of details. The use of levels of abstraction is built on thematic groupings of entities. These themes of entities allow the creation of sets of entities and relations with common characteristics. For example, a physical grouping of data, data used by a same users’ group or a same department or data within a same domain of applications. An entity located in the intersection of themes can mean duplication of data or “power struggle” while a relation between themes means possible sharing of data. Also, we tan use different views at the same level of abstraction to focus on certain aspects of the model or of a part of the model.