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Problem-Solving Methods in Perspective

Problem-Solving Methods in Perspective. Richard Benjamins University of Amsterdam. In perspective?. Knowledge components PSMs and Ontologies A standard for characterizing PSMs? PSMs in Cyberspace From ideas to practice: a community effort. IBROW. An Intelligent Brokering Service for

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Problem-Solving Methods in Perspective

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  1. Problem-Solving Methodsin Perspective Richard Benjamins University of Amsterdam

  2. In perspective? • Knowledge components • PSMs and Ontologies • A standard for characterizing PSMs? • PSMs in Cyberspace • From ideas to practice: a community effort

  3. IBROW An Intelligent Brokering Service for Knowledge-Component Reuse on the World-Wide Web Richard Benjamins

  4. Objectives of IBROW • Develop an intelligent brokering service that enables third party knowledge-component reuse through the Web • Configurable reasoning services on the web • Plug & Play of PSMs and Ontologies

  5. The agents involved

  6. Innovative aspects • Most web services broker static information • Metacrawler, Searchbroker, Ontobroker • IBROW brokers dynamic (reasoning) knowledge • Opens possibility for a new electronic market place

  7. Motivation • Topdown • make KE technology on reuse more widely accessible at lower cost • Bottom up • several PSM libraries exist, but not accessible nor interoperable • WWW is here to stay

  8. IBROW project • ESPRIT, Open Long Term Research • basic research • industrial potential • unknown risk • Partners: • University of Amsterdam, SWI (nl) • University of Karlsruhe, AIFB (de) • Open University, KMI (uk) • Artificial Intelligence Research Institute (es)

  9. Approach • Standard Product Description Language • Libraries of reusable PSMs and Ontologies • Brokering problem-solving knowledge • Interoperability • User Interface (browser)

  10. Overview • Method description language (UPML) • Brokering problem-solving knowledge • Interoperability of heterogeneous components • Conclusions

  11. What is UPML? • Starting point: CML of CommonKADS • Adds: • component-based software development • component reuse • Machine processable • enables semi-automatic system development • needed for broker

  12. The Backbone of UPML

  13. Ontology • Explicit specification of a conceptualization • can be shared by multiple reasoning components • Provide definition of • signatures • axioms used by other parts of the architecture

  14. Task • Specifies problem to be solved • by knowledge-based system • Problem definition is domain independent • enables reuse of generic problem definitions for different applications. • contrary to most approaches in software engineering

  15. Domain Models • Domain knowledge required by • problem-solving method • task definition • Three elements: characterization of • properties • assumptions • domain knowledge

  16. Problem-Solving Methods • Describe reasoning steps and types of knowledge needed to perform a task. • Two different types of PSMs: • complex problem-solving methods • primitive problem-solving methods

  17. Problem-Solving Methods • Complex problem-solving methods • decompose a task into subtasks • Primitive problem-solving methods • make assumptions about domain knowledge to perform a reasoning step • do not have an internal structure

  18. Problem-solving method

  19. Bridges, Refiners

  20. Bridges • Model relationships between two different parts of an architecture • between domain and task • task and problem-solving method

  21. Refiners • Used to express the stepwise adaptation of one type of element of a specification • a task is refined into a more specific task (design --> parametric design) • a problem-solving method is refined into a more specific PSM (search --> hill climbing)

  22. Design Rules • Architectural constraints ensure well formed specifications • The individual components must fulfill certain properties (assumptions + operational-spec --> competence of PSM) • Their connection via bridges and refiners must fulfill certain properties

  23. Editor for UPML • PROTEGE-II provides an environment for generating knowledge acquisition tools • Use of PROTEGE-II for • defining UPML meta ontology • designing editor for UPML

  24. Meta ontology of UPML

  25. Editor for UPML

  26. Browser for UPML • On2broker for • browsing UPML specifications • query interface for UPML specifications • Query Interface is a JavaTMRemote Method Invocation (RMI) Serverwhich can be consulted by any software agent

  27. The IBROW broker • Acquire customer’s problem description • Configuration • Find candidate problem-solving methods • Check their applicability wrt the KB • Integrate the PSMs into a coherent reasoner • Execution • CORBA • Web standard

  28. Two problems

  29. Characterizing PSMs • UPML provides slots for • competence of PSMs • goal of tasks • pragmatics (non functional) • ease of use • rate of success • successfully used in … • assumptions of PSMs, tasks and domains

  30. Finding PSMs • Libraries have to register at the broker • Global match in case of many PSMs • pragmatics, keywords • For promising PSMs, match competence with task goal (theorem prover) • might imply mapping and renaming

  31. Checking applicability • Check assumptions of the PSM in the KB of the customer • theorem prover • If different ontologies, derive bridges to connect PSM and KB

  32. Task-PSM bridge Locating PSMs

  33. Integrating PSMs • Impose control knowledge on the selected PSMs • chain inputs and outputs • consider UPML’s operational descriptions • exploit existing task structures

  34. Execution • CORBA • the configured problem-solver is a collection of clients • each PSM is a server • the KB is a server • Lisp Server (using Web standards) • client can also query Lisp Server • Broker controls which client sends requests

  35. Overall picture

  36. Small demo

  37. Summary of Achievements • Distributed knowledge-intensive applications • Competence-oriented component libraries with explicit models based on a uniform framework • (Semi-) automated construction of bridges between components and refiners • Interoperability through CORBA and WWW standards • Powerful brokering facilities

  38. Open Issues • Formalization (pragmatics) • CORBA wrapping of (legacy) KBs • Bridges and refiners (theory) • Architectures

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