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Chapter 4. Mining Association Rules from... > THE FUZZY MULTIDIMENSIONAL MODEL

THE FUZZY MULTIDIMENSIONAL MODEL

Although there is no standard multidimensional model, we shall briefly introduce the common characteristics of the first models proposed in literature. In classical multidimensional models, we can distinguish two different types of data: on the one hand, we have the facts being analyzed, and on the other, the dimensions that are the context for the facts. Hierarchies may be defined in the dimensions (Agrawal, Gupta, & Sarawagi, 1995; Kimball, 1996; Cabibbo & Torlone, 1997; Cabibbo & Torlone, 1998).

The different levels of the dimensions allow us to access the facts at different levels of granularity. In order to do so, classical aggregation operators are needed (maximum, minimum, average, etc.). Other models, which do not define explicit hierarchies on the dimensions, use other mechanisms to change the detail level (Li & Wang, 1996; Datta & Thomas, 1999). The model proposed by Gray et al. (Gray, Chaudhuri, Bosworth, Layman, Reichart, & Venkatrao, 1997) uses a different approach. This model defines two extensions of the relational group by (rollup and cube) that are used to group the values during the aggregation process.


  

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