1 a conceptual framework of data mining y.y. yao department of computer science, university of...
TRANSCRIPT
1
A Conceptual Framework of Data Mining
Y.Y. Yao
Department of Computer Science, University of ReginaRegina, Sask., Canada S4S 0A2
[email protected]://www.cs.uregina.ca/~yyao
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, 1982.“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 the nature of data mining
The study of
data mining
methods
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 foundationsThe 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 mindand in the abstract.
Technique level
The study of knowledge & knowledge discovery in machine.
Application level
The study of the applications of discoveredKnowledge.
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 viewA concept is described jointly by its intension and extension.
In ten sion E x ten s ion
C o nce p t
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
DifferentiationDifferentiation
IntegrationIntegration
AggregationAggregation
CharacterizationCharacterization
ConceptformationConcept
formation
30
Philosophy level study of concept
Classical view
AggregationAggregation
CharacterizationCharacterization
vs.
Differences
ConceptformationConcept
formation
31
Philosophy level study of concept
Classical view
AggregationAggregation
CharacterizationCharacterization
vs.
Differences
Similarities
ConceptformationConcept
formation
32
Philosophy level study of concept
Classical view
AggregationAggregation
CharacterizationCharacterization
vs.
Extension
Intension
ConceptformationConcept
formation
33
Philosophy level study of concept
ContextContext
HierarchyHierarchy
ConceptlearningConceptlearning
ConceptformationConcept
formation
34
Philosophy level study of concept
ContextContext
HierarchyHierarchy
ConceptlearningConceptlearning
ConceptformationConcept
formation
35
Technique level study of concept
Search for the intensionSearch for the intension
Given a context -Given a context -
Search for the extensionSearch for the extension
Analyze the concepts relationshipAnalyze the concepts relationship
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.
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.