Transcript 1. 서론

6. 전문가 시스템
전문가 시스템(Expert Systems)
 특정의 문제를 해결하기 위해 특정의 전문적인 지식을 기
반으로 실행되는 컴퓨터 시스템
 특정 문제 영역에서 그 영역의 인간 전문가가 의사 결정을
내리는 것과 유사하게 동작하는 컴퓨터 시스템
 인공지능 분야에서 상업적으로 성공한 대표적 분야
 기능적 측면에서 필요한 요소




추론 기능
사용자-시스템 간의 상호작용에 의한 데이터 획득
결론의 정당성(Justification)
모듈 구조(Modular architecture)
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 전문가 시스템의 배경
매우 특화된 프로그램을
생성하기 위해 좁은
문제 영역에 대한 고수준의
정제된 지식을 이용
PROGRAM POWER
high
표현 및 탐색 기능을
향상시키는 일반 방법론을
찾고, 특화된 프로그램을
구축하고자 함
문제해결을 위한 일반
방법론을 찾고, 범용-목적
low
프로그램을 구축하고자 함
1960
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
1970
1980
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 Breakthrough

To make a program intelligent, provide it with lots of highquality, specific knowledge about some problem area
 Building
Expert Systems
Knowledge Engineering: The process of building an expert
system
 Knowledge Engineer: Expert-system builder
 Need the interaction between the KE and human experts

– The KE extracts procedures, strategies, and rules of thumb for
problem solving
– The KE builds this knowledge into the expert system

Result: a program that solves problems like the human experts
Queries, Problems
Domain
Expert
Knowledge
Engineer
Answers, Solutions
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Strategies,
Rules-of-thumb,
Domain rules
Expert
System
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 전문가 시스템 구축과정
Domain
Expert
Toolbuilder
Builds
Expert
System
Building
Tool
Extends
and tests
Interviews
Uses
Knowledge
Engineer
Builds,
refines,
and tests
Expert
System
End-User
Uses
Adds
data
Clerical
Staff
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
Basic Components of Expert System (ES)
 Experts/Knowledge Engineer
 Knowledge Base
 Inference Engine
 User Interface
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
Basic Concepts of Expert Systems - cont.
 Experts
 Recognizing
and formulating the problem
 Solving the problem quickly and properly
 Explaining the solution
 Learning from experience
 Restructuring knowledge
 Determining relevance
 Expertise is the extensive, task-specific knowledge
acquired from training, reading and experience
 Theories
about the problem area
 Hard-and-fast rules and procedures
 Rules (heuristics)
 Global strategies
 Meta-knowledge (knowledge about knowledge)
 Facts
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
Basic Concepts of Expert Systems - cont.
 Transferring Expertise
 Objective
of an expert system
To transfer expertise from an expert to a computer system and
 Then on to other humans (non-experts)

 Activities
Knowledge acquisition
 Knowledge representation
 Knowledge inference
 Knowledge transfer to the user

 Knowledge
is stored in a knowledge base
 Two knowledge types

Fact / Procedures(rules)
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
The Knowledge Engineer
 Helps the expert(s) structure the problem area by
interpreting and integrating human answers to questions,
drawing analogies, posing counterexamples, and
bringing to light conceptual difficulties
 Knowledge Acquisition Subsystem
 Knowledge
acquisition is the accumulation, transfer and
transformation of problem-solving expertise from experts and/or
documented knowledge sources to a computer program for
constructing or expanding the knowledge base
 Usually also the System Builder
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
The User
 Possible Classes of Users
A
non-expert client seeking direct advice - the ES acts as a
Consultant or Advisor
 A student who wants to learn - an Instructor
 An ES builder improving or increasing the knowledge base a Partner
 An expert - a Colleague or Assistant
 The Expert and the Knowledge Engineer Should
Anticipate Users' Needs and Limitations When
Designing ES
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
Knowledge Base
 The knowledge base contains the knowledge necessary
for understanding, formulating, and solving problems
 Two Basic Knowledge Base Elements
 Facts
 Special
heuristics, or rules that direct the use of knowledge
 Knowledge is the primary raw material of ES
 Incorporated knowledge representation
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
Inference Engine
 The brain of the ES
 The control structure or the rule interpreter
 Provides a methodology for reasoning
 The computer is programmed so that it can make
inferences
 Major Element
 Interpreter
 Scheduler
 Consistency
인공지능: 개념 및 응용
Enforcer
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
User Interface
 Language processor for friendly, problem-oriented
communication
 NLP, or menus and graphics
 Explanation subsystem
 Traces
responsibility and explains the ES behavior by
interactively answering questions
Why?
How?
What?
(Where? When? Who?)
 Knowledge

Refining System
Learning for improving performance
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 Expert System Building Tool(not the expert system)
Expert System
Building Tool
Expert System
Building Language
Expert
System
Support
Environment
User
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 What Good Are Expert Systems
 Why
not use real Experts?
→ Why do we develop expert systems

Comparing human and artificial expertise: the good news
The Good News
Human Expertise
Artificial Expertise
Perishable
Permanent
Difficult to transfer
Easy to transfer
Difficult to document
Easy to document
Unpredictable
Consistent
Expensive
Affordable
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 Why
keep a human in the loop?
Why not eliminate human expert replacing them with expert
systems?
 Comparing human and artificial expertise: the bad news

The Bad News
Human Expertise
Creative
Adaptive
Sensory experience
Broad focus
Commonsense knowledge
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도용태 김일곤 김종완 박창현 공저
Artificial Expertise
Uninspired
Needs to be told
Symbolic input
Narrow focus
Technical knowledge
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 How Are Expert Systems Organized?
 Organizing
Knowledge
Knowledge: The information a computer program needs with
which it can behave intelligently

 take the form of facts and rules
 sometimes considers uncertainty

 Many

of rules in expert systems are heuristics
Comparing Algorithmic with Heuristic methods
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 The structure of an Expert System
Expert System
Knowledge Base
(Domain Knowledge)
Knowledge
Representations
Facts
Rules
Interpreter
Scheduler
Inference Engine
(General Problem-Solving
Knowledge)
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 Knowledge-Based Systems
Artificial
Intelligence
Programs
Exhibit intelligent
behavior by skillful
application of heuristics
Knowledge-based
Systems
Make domain knowledge
explicit and separate from
the rest of the system
Expert
Systems
Apply expert knowledge
to difficult, real world
problems
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 How Do Expert Systems Differ from Conventional
Programs
 Comparison
of data processing and knowledge engineering
Date Processing
Representations and use
of data
Algorithmic
Repetitive Process
Effective manipulation
of large data bases
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Knowledge Engineering
Representation and use of
knowledge
Heuristic
Inferential process
Effective manipulation of large
knowledge bases
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 Basic Characteristics of an Expert Systems
 Characteristics
of an expert system that distinguish it from
a conventional program
Expert System
Expertise
Symbolic reasoning
Depth
Self-Knowledge

Exhibit expert performance
Have high level of skill
Have adequate robustness
Represent knowledge symbolically
Reformulate symbolic knowledge
Handle difficult problem domains
Use complex rules
Examine its own reasoning
Explain its operation
Expert Systems sometimes make mistakes
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 What Have Expert Systems Been Used For?
 Basic
Activities of Expert Systems
Generic Categories
Category
Problem Addressed
Interpretation
Prediction
Diagnosis
Design
Planning
Monitoring
Debugging
Repair
Instruction
Inferring situation descriptions from sensor data
Inferring likely consequences of given situations
Inferring system malfunctions from observables
Configuring objects under constraints
Designing actions
Comparing observations to expected outcomes
Prescribing remedies for malfunctions
Executing plans to administer prescribed remedies
Diagnosing, debugging, and repairing user
behavior
Governing overall system behavior
Control
인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications
6. 전문가 시스템
 Application

Areas for Expert systems
Chemistry
– DENDRAL, MOLGEN

Computer Systems
– XCON

Electronics
– ACE, EURISKO, SOPHIE

Geology
– PROSPECTOR

Medicine
– MYCIN, ONCOCIN, GUIDON
Military
 Engineering

인공지능: 개념 및 응용
도용태 김일곤 김종완 박창현 공저
Artificial Intelligence: Concepts and Applications