Artificial Intelligence: Chapter 4 Introduction to Knowledge Base Systems

Artificial Intelligence: Chapter 4 

Introduction to Knowledge Base Systems

What is a knowledge-based system?

­A system which is built around a knowledge base. i.e. a collection of knowledge, taken from a human, and stored in such a way that the system can reason with it.



What is knowledge?

­Knowledge is the sort of information that people use to solve problems.



A knowledge-based agent

A knowledge-based agent includes a knowledge base and an inference system.A knowledge base is a set of representations of facts of the world. Each individual representation is called a sentence. The sentences are expressed in a knowledge representation language.


The agent operates as follows:


1. It TELLs the knowledge base what it perceives.

2. It ASKs the knowledge base what action it should perform.

3. It performs the chosen action.



Architecture of a knowledge-based agent


Knowledge Level.
­The most abstract level: describe agent by saying what it knows.
Example: A taxi agent might know that the Golden Gate Bridge connects San Francisco with the Marin County.


Logical Level.


­The level at which the knowledge is encoded into sentences.
Example: Links(GoldenGateBridge, SanFrancisco, MarinCounty).



Implementation Level.

­The physical representation of the sentences in the logical level.
­Example: ‘(links goldengatebridge sanfrancisco marincounty)


Expert systems


What is an expert system?

A particular kind of knowledge-based system. One in which the knowledge, stored in the knowledge base, has been taken from an expert in some particular field.
Therefore, an expert system can, to a certain extent, act as a substitute for the expert from whom the knowledge was taken.

 

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Artificial Intelligence: Chapter 4 Introduction to Knowledge Base Systems