A symbol structure is composed of a number of instances (or token) of
symbols related in some physical way.
At any instant of time the system will contain a collection of those symbol
structures, system also contains a collection of processes which operate an
expressions to produce other expressions, processes of creation,
modifications, processes of creation, modification, reproduction and
The physical symbol system hypothesis:
A physical symbol system has the necessary and sufficient means for general
What is an AI Technique?
Intelligence requires knowledge but the knowledge possess some less
desirable properties such as
It is voluminous
It is hard to characterize accurately.
It is constantly changing.
It differs from data which is organised in some way corresponding to the
way in which it will be used.
Thus we can define that an AI technique is a method which exploits
knowledge which should be represented in such a way that:
The knowledge captures generalizations: Each individual situation need not
be represented separately and the situations that share important
properties are grouped together.
Knowledge can be understood by people who must provide.
It can be modified easily to correct errors and to reflect the changes in the
world and in our world view.
It can be used in many situations even if it is not totally accurate or
By narrowing down the range of possibilities the sheer bulk of data can be
reduced, for being considered. The AI techniques must be designed
keeping in view the constraints imposed by AI problems.
How to build a system to solve a particular problem?
1) Define the problem precisely
a) What will be the specification of initial state and final state of acceptable
solution to the problem.
2) Analyse the problems:
a) Appropiate technique be selected for solving problem.
3) Isolate and represent the tasks knowledge which is necessary to solve the
4) Choose the best problem solving technique and apply it to solve the particular