1 A Conceptual Framework of Data Mining Y.Y. Yao Department of Computer Science, University of Regina Regina, Sask., Canada S4S 0A2

2 Acknowledgements Thanks to Professors Wang Jue Zhou Zhi-Hua Zhou Aoying for the kind invitation and this opportunity.

3 Motivations “The question typically is not what is an ecosystem, but how do we measure certain relationships between populations, how do some variables correlate with other variables, and how can we use this knowledge to extend our domain.” Salthe, S.N. Evolving Hierarchical Systems, Their Structure and Representation

4 Motivations “… the scientist is usually not, on the other hand, a self-conscious epistemologist. That would mean going beyond his area of narrow training for the purpose of questioning its point. Functioning as a scientist means functioning within the rules of a game learned during the apprenticeship in which examination of the philosophic foundations of the game plays a characteristically tiny role.”

5 Motivations (Data Mining) One is more interested in the algorithms for finding “knowledge”, but not what is knowledge. One is more interested in a more implementation-oriented view or framework of data mining, rather than a conceptual framework for the understanding of the nature of data mining.

6 Data mining Function-oriented approaches: Requirements Theory-oriented approaches: Mathematical/statistical methods Procedure/process-oriented approaches: KDD processes There does not exist a concept framework for data mining.

7 Motivations (General) We are more interested in doing than understanding. We are more interested in actual systems and methods than a powerful point of view. We are more interested in solving a real world problem than acquisition of knowledge. We have enough knowledge, but not sufficient wisdom in using the knowledge.

8 Motivations Four international workshops have been held on foundations of data mining. There still does not exist a well accepted and non-controversial framework. Many papers do not cover the “foundations of data mining”.

9 The question How to view and study data mining? What can we learn from our experiences? From other fields. From well established branches.

10 Knowledge structure and problem solving in physics Reif and Heller, “ Effective problem solving in a realistic domain depends crucially on the content and structure of the knowledge about the particular domain. ” The knowledge about physics “ specifies special descriptive concepts and relations described at various level of abstractness, is organized hierarchically, and is accompanied by explicit guidelines specifying when and how this knowledge is to be applied. ”

11 Knowledge structure and education Experts and novices differ in their knowledge organization. Experts are able to establish multiple representations of the same problem at different levels of granularity. Experts are able to see the connections between different grain- sized knowledge.

12 Cognitive Science Posner, 1989 According to the cognitive science approach, to learn a new filed is to build appropriate cognitive structures and to learn to perform computations that will transform what is know into what is not yet known.

13 A New View Data mining as a field of study, rather than simply a collections of algorithms, or a combination of several fields. The study of data mining may be viewed as a scientific enquiry into the nature of data mining and the scope of data mining methods.

14 Three basic questions What are the foundations of data mining? What is the scope of the foundations of data mining? What are the differences between existing researches and the research on the foundations of data mining?

15 A potential solution The study of the nature of data mining The study of data mining methods The philosophical foundations The theoretical foundations The mathematical foundations The philosophical foundations The theoretical foundations The mathematical foundations The technological foundations

16 A conceptual framework A layered framework can be established. Each layer/level deals with the problem in different contexts: in mind and in the abstract in machine application.

17 A layered model of Data Mining Philosophy level Algorithm/technique level Application level Philosophy layer Technique layer Application layer

18 A layered model Philosophy level: What is knowledge? The study of knowledge & knowledge discovery in mind and in the abstract. What is knowledge representation? How to express and communicate knowledge? What is the relationship between knowledge in mind and in real world? How to classify knowledge? How to organize knowledge? Philosophy layer Technique layer Application layer

19 A layered model Technique level: How to discover knowledge? The study of knowledge & knowledge discovery in machine. How to code, storage, retrieve knowledge in computer? How to develop an efficient algorithm? How to improve an existing technique? Philosophy layer Technique layer Application layer

20 A layered model Application level: How to use the discovered knowledge The study of the applications of discovered Knowledge. Is the discovered knowledge useful? Is the discovered knowledge meaningful? How to use the knowledge? Philosophy layer Technique layer Application layer

21 A layered model Philosophy level The study of knowledge & knowledge discovery in mind and in the abstract. Technique level The study of knowledge & knowledge discovery in machine. Application level The study of the applications of discovered Knowledge. 1.The division among the three levels is not a clear cut, and may have overlaps with each other. 2.The inner layers establish a foundation for the outer layers. 3.The outer layers may raise questions for the inner layers.

22 A layered model of KDD The results from philosophy level will provide guideline and set the stage for the algorithm and application levels. Philosophical study does not depend on the availability of specific techniques. Technical study is not constrained by a particular application. The existence of a type of knowledge in data is unrelated to whether we have an algorithm to extract it. The existence of an algorithm does not necessarily imply that the discovered knowledge is meaningful and useful

23 A layered model of KDD The three levels represent the understanding, discovery, and utilization of knowledge. Any of them is indispensable in the study of intelligence and intelligent systems. They must be considered together in a common framework through multi-disciplinary studies, rather than in isolation.

24 Application of the layered framework Concept formation and learning can be studied within the layered framework. The reconsideration brings a better understanding of the problem.

25 Application of the layered framework Concept formation and learning can be studied within the layered framework. The reconsideration brings a better understanding of the problem.

26 Philosophy level study of concept Classical view A concept is described jointly by its intension and extension.

27 Philosophy level study of concept

28 Philosophy level study of concept Two basic issues of concept formation Aggregation aims at the identification of a group of objects so that they form the extension of a concept. Characterization attempts to describe a set of objects as their intension.

29 Philosophy level study of concept Classical view Differentiation Integration Aggregation Characterization Concept formation Concept formation

30 Philosophy level study of concept Classical view Aggregation Characterization vs. Differences Concept formation Concept formation

31 Philosophy level study of concept Classical view Aggregation Characterization vs. Differences Similarities Concept formation Concept formation

32 Philosophy level study of concept Classical view Aggregation Characterization vs. Extension Intension Concept formation Concept formation

33 Philosophy level study of concept Context Hierarchy Concept learning Concept learning Concept formation Concept formation

34 Philosophy level study of concept Context Hierarchy Concept learning Concept learning Concept formation Concept formation

35 Technique level study of concept Search for the intension Given a context - Search for the extension Analyze the concepts relationship

36 Technique level study of concept Intensions of concepts defined by a language

37 Technique level study of concept Intensions of concepts defined by a language

38 Technique level study of concept Conjunctive concept space

39 Technique level study of concept Conjunctive concept space

40 Technique level study of concept

41 Technique level study of concept Extensions of concepts defined by an information table

42 Technique level study of concept

43 Technique level study of concept Extensions of concepts defined by an information table

44 Technique level study of concept Relationship between concepts in an information table

45 Technique level study of concept Relationship between concepts in an information table

46 Technique level study of concept Probabilistic measures:

47 Technique level study of concept Probabilistic measures:

48 Technique level study of concept Concept learning as search

49 Technique level study of concept Concept learning as search

50 Technique level study of concept Concept learning as search

51 Technique level study of concept Concept learning as search

52 Application level study of concept The main purposes of science are to describe and predict, to improve or manipulate the world around us, to explain our world. Concepts learning should serve the same purposes.

53 Application level study of concept to describe

54 Application level study of concept to predict

55 Application level study Domain specific The usefulness of concepts needs to be defined and interpreted based on other more familiar notions.

56 Conclusions It is important to treat data mining as a field of scientific enquiry. One needs to consider all aspects of data mining. The layered framework may provide a better understanding of data mining.

57 Conclusions We need to find the cognitive structures or knowledge structures of data mining. We need to move beyond algorithm and application centered views of data mining. We need to avoid seductive semantics.

58 Conclusions Data mining can be studied in the context of scientific discovery and research methods. Data mining and machine learning systems may be viewed as support systems for the exploration of data, such as research support systems.

59 Thank you! The ideas are preliminary and need fine tune. You comments, suggestions, and criticisms are welcome!