What is an Expert System?
An Expert System is a computer system
that emulates the decision-making
ability of a human expert.
Expert systems are designed to solve
complex problems by reasoning about
knowledge, like an expert.
Expert systems are:
Knowledge based systems
Part of the Artificial Intelligence field
Computer programs that contain some
subject-specific knowledge of one or more
Systems that utilize reasoning capabilities
and draw conclusions.
4 Major Components
Every expert system consists of four principal
The rule base or knowledge base
The inference engine
1) The rule base or knowledge base
The knowledge base is the collection of
facts and rules which describe all the
knowledge about the problem domain
Contain everything necessary for
understanding, formulating and solving a
Stores all relevant
information, data, rules, cases, and
relationships used by the expert system
2) WORKING MEMORY (SHORT
Contains facts about a problem that are
discovered during consultation with the expert
System matches this information with
knowledge contained in the knowledge base to
infer new facts.
The conclusion reach will enter the working
3) The inference engine
The inference engine is the part of the system
that chooses which facts and rules to apply when
trying to solve the user’s query.
It taps the knowledge base and working memory
to derive new information and solve problems
The inference engine is a computer program
designed to produce reasoning on rules
It is based on logic
4) THE USER INTERFACE
The user interface is the part of the system which takes
in the user’s query in a readable form and passes it to
the inference engine. It then displays the results to the
The user communicates with the expert system
through the user interface.
It allows the user to query the system, supply
information and receive advice.
The aims are to provide the same form of
communication facilities provided by the expert.
The code that controls the dialog between the user and
Types of Expert Systems
Knowledge represented by series of rules
Knowledge represented by frames
Several approaches are combined, usually rules and frames
Models simulate structure and functions of systems
Ready made packages for general use
Meet specific need
Reduce employee training costs
Reduce the time needed to solve problems.
Combine multiple human expert intelligences
Reduce the amount of human errors.
Never "forgets" to ask a question,
Ability to solve complex problems
Consistent answers for repetitive decisions, processes and