1. Models of Situations

2. A computer model of a system is a program and data which behaves like the real thing, e.g. a driving simulation, a graph of business profits, a robot arm.

3. A model:  may copy only part of the actual system;  is determined by rules usually built into the program;  can be used to forecast what will happen in the real world.

4. A model can be used in order to:  avoid danger;  save money;  save time;  help make difficult decisions;

5.  A computer model may run at the same rate, faster or slower than the real system. Many computer models have a mathematical basis with:  real quantities represented by variables in the program;  rules for the models behaviour contained in formulae;

6. In practise computer models can be produced using:  spreadsheets;  computer graphics, including charts;  simulation programs  virtual reality systems;  expert systems;

7. The stages in producing a model are:  analyse the problem;  design the model;  produce the model;

8.  A computer simulation of a system is a program which models the system.  A virtual reality simulation is a simulation which appears real:  the user feels a part of the simulation.  the simulation may be experienced through all senses.  A expert system is a computer program which simulates the knowledge and experience of a human expert.  A expert system consists of:  a knowledge base of rules and facts;  a program to work out a solution of the user's problem.