TAILIEUCHUNG - Data Mining Concepts and Techniques phần 9

Có hai phương pháp chính cho sự liên kết chuỗi nhiều khoảng. Phương pháp đầu tiên làm giảm một sự liên kết nhiều với một loạt các sự sắp xếp pairwise và sau đó kết hợp các kết quả. Feng-Doolittle phương pháp liên kết phổ biến thuộc về cách tiếp cận này. Feng-Doolittle liên kết đầu tiên tính toán tất cả các sự sắp xếp, | 596 Chapter 10 Mining Object Spatial Multimedia Text and Web Data via its closely related linkages in the class composition hierarchy. That is in order to discover interesting knowledge generalization should be performed on the objects in the class composition hierarchy that are closely related in semantics to the currently focused class es but not on those that have only remote and rather weak semantic linkages. Construction and Mining of Object Cubes In an object database data generalization and multidimensional analysis are not applied to individual objects but to classes of objects. Since a set of objects in a class may share many attributes and methods and the generalization of each attribute and method may apply a sequence of generalization operators the major issue becomes how to make the generalization processes cooperate among different attributes and methods in the class es . So how can class-based generalization be performed for a large set of objects For classbased generalization the attribute-oriented induction method developed in Chapter 4 for mining characteristics of relational databases can be extended to mine data characteristics in object databases. Consider that a generalization-based data mining process can be viewed as the application of a sequence of class-based generalization operators on different attributes. Generalization can continue until the resulting class contains a small number of generalized objects that can be summarized as a concise generalized rule in high-level terms. For efficient implementation the generalization of multidimensional attributes of a complex object class can be performed by examining each attribute or dimension generalizing each attribute to simple-valued data and constructing a multidimensional data cube called an object cube. Once an object cube is constructed multidimensional analysis and data mining can be performed on it in a manner similar to that for relational data cubes. Notice that from the .

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