Knowledge Management Knowledge Management Challenges in Knowledge Challenges in Knowledge Discovery Systems Discovery Systems Mykola Pechenizkiy , Seppo Puuronen Department of Computer Science University of Jyväskylä Finland Alexey Tsymbal Department of Computer Science Trinity College Dublin Ireland TAKMA’05 Copenhagen, Denmark August 22-26, 2005
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Knowledge Management Challenges in Knowledge Discovery Systems Mykola Pechenizkiy, Seppo Puuronen Department of Computer Science University of Jyväskylä.
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Knowledge Management Knowledge Management Challenges in Knowledge Challenges in Knowledge
Discovery SystemsDiscovery Systems
Mykola Pechenizkiy, Seppo Puuronen Department of Computer Science
University of Jyväskylä Finland
Alexey TsymbalDepartment of Computer Science
Trinity College DublinIreland
TAKMA’05 Copenhagen, Denmark August 22-26, 2005
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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OutlineOutline
• Introduction– KDD– Selection of DM strategy for a problem at hand– Meta-learning
• Our goal– To propose a knowledge-driven approach to enhance
the selection of DM strategies in KDSs.
• Need for KM• What are the challenges
– KM processes wrt problem of DM strategy selection
• Further research• Discussion
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Knowledge discovery as a processKnowledge discovery as a process
Fayyad, U., Piatetsky-Shapiro, G., Smyth, P., Uthurusamy, R., Advances in Knowledge Discovery and Data Mining, AAAI/MIT Press, 1997.
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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CRISP-DMCRISP-DM
http://www.crisp-dm.org/
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
Reinartz, T. 1999, Focusing Solutions for Data Mining. LNAI 1623, Berlin Heidelberg.
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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The Search for Scientific Methods and Meta-The Search for Scientific Methods and Meta-LearningLearning
• Adequate scientific methods make induction easier with a smaller number of examples.
• The choice of methods needs to be based on a higher level induction or on meta-learning in the context of machine learning.
• “knowledge concerning the most appropriate method for a given goal can be obtained by induction on the database of history of science a collection of problems of different methods, different goals and different degrees of success” [Laudan]
• Meta-learning can produce rules concerning the use of the alternative strategies, methodological knowledge, or correct predictions concerning the best rank of strategies for a new task.
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Dynamic Selection of DM Dynamic Selection of DM MethodsMethods
• … in KDSs has been under active study
• 2 contexts of dynamic selection:– multi-classifier systems that apply different
ensemble techniques (Dietterich, 1997). • Their general idea is usually to select one classifier
on the dynamic basis taking into account the local performance (e.g. generalisation accuracy) in the instance space.
– multistrategy learning (Michalski)• applies a strategy selection approach which takes
into account the classification problem- related characteristics (meta-data).
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Selection of the most appropriate DM techniqueSelection of the most appropriate DM technique
• Motivation– No Free Lunch theorem; – many empirical studies show
• one learning strategy can perform significantly better than another strategy on a group of problems that are characterised by some properties (Kiang, 2003).
• Problem– Selection is usually not straightforward. – some knowledge is required for making a decision about appropriate
techniques’ selection and DM strategy construction for a problem at hand.
• We distinguish 2 levels of knowledge:– the knowledge extracted from data that represents the problem to be
mined by means of applying a DM technique – the higher-level knowledge (from the KDS perspective) required for
managing techniques’ selection, combination and application => meta-knowledge.
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Meta-learningMeta-learning
• or “learning to learn” – the effort to automatically induce dependencies:– learning tasks learning strategies.
• based on the assumptions that it is possible – to evaluate and compare learning strategies, – to measure the benefits of early learning on
subsequent learning, – to use such evaluations to reason about
learning strategies• select useful ones and disregard the useless or
misleading strategies (Schmidhuber et al., 1996).
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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in Meta-learning …in Meta-learning …
• in the context of classifier ensembles, where only the data itself is used to make decisions about method selection,– rather good practical results are shown in experiments
supported by theoretical studies as well;
• in dynamic integration of DM strategies for a data set at hand: – a multistrategy approach based on the ideas of
constructive induction and conceptual clustering (Michalski, 1997)
– several studies on automatic classifier selection via meta-learning (Kalousis, 2002)
• No practical success!
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Meta-LearningMeta-Learning
Suggested technique
A new data set Meta-model
Collection of data sets
Collection of techniques
Meta-learning space
Performance criteria
Knowledge repository
Evaluation
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Problems with Meta-Learning for Problems with Meta-Learning for DM SSDM SS
• Representativeness of meta-data samples– Meta-learning space is large
– Computationally expensive to produce meta-data samples
– Curse of dimensionality
– Many possible irrelevant features wrt collected/produced meta-data
• Complexity of statistical measures– Why do we need to spend time to characterize the
dataset if we can use this time to try different DM approaches and select the best one?
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Our goal and focus: KM Our goal and focus: KM perspectiveperspective
• to propose a knowledge-driven approach to enhance the dynamic integration of DM strategies in knowledge discovery systems;
• focus on KM aimed to organise a systematic process of knowledge capture and refinement over time.
• We consider the basic knowledge management processes of– knowledge creation and identification,
– representation, collection and organization,
– sharing and integration,
– adaptation and application
with respect to the introduced concept of meta-knowledge.
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Introducing KM to DM SSIntroducing KM to DM SS
• Generally, the problem of knowledge capture, storage, and dissemination is similar to data and information management in ISs, and therefore some executives prefer to view KM as a natural extension to IS functions (Alavi and Leidner, 1999).
• Zack (1999) – the most practical way to define KM is to show on the existing IT infrastructure the involvement of:
– (1) knowledge repositories,
– (2) best-practices and lessons-learned systems,
– (3) expert networks [these are DM experts], and
– (4) communities of practice [these are end-users].
Knowledge Creation & Acquisition
Knowledge Organization &
Storage
Knowledge Distribution & Integration
Knowledge Adaptation & Application
Knowledge Evaluation, Validation and Refinement
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Transformations of data and knowledge Transformations of data and knowledge conceptsconcepts
Knowledge is “justified belief that increases an entity’s capacity for effective action” (Nonaka, 1994).A long history of epistemological debates, and discussion of knowledge from different perspectives in Polanyi (1962).
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Different types of knowingDifferent types of knowing
Knowing Analysis Context that and what Conceptual concepts, relationships, i.e. declarative knowledge how Functional hypothesis, i.e. procedural knowledge where Spatial data set characterization when Temporal temporal context why Causal higher-level abstraction who Organizational integration, sharing how much Economical benefits, risks, resources what for Strategic business DM goals, domain knowledge
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Knowledge distribution and knowledge Knowledge distribution and knowledge integration integration
4 potential sources of knowledge that has to be integrated in the repository of KDS system:
– (1) knowledge from an expert in data-mining, knowledge discovery, statistics and related fields;
– (2) knowledge from a data-mining practitioner;
– (3) knowledge from laboratory experiments on synthetic data sets; and, finally,
– (4) knowledge from field experiments on real-world problems.
– Beside this, research and business communities, and similar KDSs themselves can organize different trusted networks, where participant are motivated to share their knowledge.
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Knowledge Repository LifecycleKnowledge Repository Lifecycle (1 (1 of 2)of 2)
• Since the repository is created it tends to grow and at some point it naturally begins to collapse under its own weight, requiring major reorganization. – needs for continuously update,
• some content needs to be deleted (if misleading), deactivated or archived (if it is potentially useful).
• if similar contributions are combined, generalized and restructured, the content may become less fragmented and redundant.
• The process of filtering knowledge claims into accepted or suppressed is important – when a plenty of claims are produced automatically they
need to be filtered automatically.
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Knowledge Repository LifecycleKnowledge Repository Lifecycle (2 (2 of 2)of 2)
• “knowing when” and “knowing where” contexts: – when the environment changes, all of the general rules without
specifying the context could become invalid.
– some knowledge should exist that would guide an organization to change the repository when the environment calls for it.
• Some knowledge claims are naturally in constant competition with the other claims.– Disagreements within the knowledge repository need to be
resolved by means of generalization of some parts and contextualization of the others.
• In order to increase the quality and validity of knowledge, it needs to be continually tested, improved or removed.
• Some basic principles of triggers can be introduced
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Knowledge validity and knowledge Knowledge validity and knowledge qualityquality
• The contexts “knowing when” and “knowing where” can be discovered before it appears in a real situation.
– Active learning– Zooming in and zooming out procedures – Search for balance between generality, compactness, interpretability, and
understandability and sensitiveness to the context, exactness, precision, and adequacy of (meta-)knowledge.
– context conditions can be important for knowledge quality estimation
• The quality of knowledge can be estimated by its ability to help a KDS produce solutions faster and more effectively.
• Knowledge claims have both a degree of utility and a degree of satisfaction.
• To determine the relative quality of a validated knowledge claim, evaluation criteria should be defined:
– complexity, usefulness, and predictive power are well formalised and easy to estimate;
– understandability, reliability of source, explanatory power are rather subjective and therefore inaccurate.
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Limitations Limitations
• The goal of KM here is to make more effective and efficient use of available DM techniques.
• The most important issues in knowledge management:– (1) executive/strategic management,
– (2) operational management,
• the identification of available knowledge,
• seeking ways to capture it in a KM process,
• and analysing the ability to design an KM (sub)system including its tools and applications
– (3) costs, benefits, and risks management, and
– (4) standards in the KM technology and communication.
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Further Research
Knowledge Creation & Acquisition
Knowledge Organization &
Storage
Knowledge Distribution & Integration
Knowledge Adaptation & Application
Knowledge Evaluation, Validation and Refinement
• Implementation of presented knowledge-driven framework for a KDS that contains a limited number of DM techniques of a certain type– Feature extraction techniques and classification
techniques
• Evaluation of the framework in practice for real-world problems in a distributed environment
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TAKMA’05 Copenhagen, Denmark August 22-26, 2005Knowledge Management Challenges in Knowledge Discovery Systems by Pechenizkiy, Tsymbal,
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Thank You!Thank You!
Contact Info:
Mykola Pechenizkiy
Department of Computer Science and Information Systems,