Introduction to Knowledge Representation：知识表示方法的介绍.ppt

Introduction to Knowledge Representation
11th September 2006
Dr Bogdan L. Vrusias
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Bogdan L. Vrusias © 2006
11th September 2006
Bogdan L. Vrusias © 2006
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Contents
Defining Knowledge Representation
Knowledge Representation Schemes
works
Taxonomy
Ontology
11th September 2006
Bogdan L. Vrusias © 2006
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Knowledge Representation
'A representation is a set of conventions about how to describe a class of things. A description makes use of the conventions of a representation to describe some particular thing.' (Winston 1992:16).
'Good representations make important objects and relations explicit, expose natural constraints, and bring objects and relations together' (ibid: 45)
The representation principle:
Once a problem is described using an appropriate representation, the problem is almost solved.
11th September 2006
Bogdan L. Vrusias © 2006
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Starting with an Example
The Farmer, The Fox, The Goose and The Grain:
The farmer must get a fox, a goose and a sack of grain across a river, however his boat is small and he can only carry one thing at a time. His problem is that if he leaves the fox with the goose the goose will be eaten, and if he leaves the goose with the grain, the grain will be eaten…
A good representation makes it easier for us to solve the problem:
Draw possible binations in a diagram.
Arrange binations in order.
Link appropriate arrangements to represent boat trips.
Problem is solved!
11th September 2006
Bogdan L. Vrusias © 2006
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Grain
Fox
Farmer
Goose
Farmer
Goose
Grain
Fox
Farmer
Fox
Goose
Grain
Fox
Grain
Farmer
Goose
Farmer
Fox
Grain
Goose
Goose
Farmer
Fox
Grain
Farmer
Goose
Fox
Grain
Farmer
Goose
Fox
Grain
Fox
Farmer
Goose
Grain
Farmer
Fox
Goose
Grain
11th September 2006
Bogdan L. Vrusias © 2006
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Knowledge Representation Schemes
A number of knowledge representation schemes (or formalisms) have been used to represent the knowledge of humans in a systematic manner. This knowledge is