Control Strategies

Control Strategy

Control strategy is a strategy by which one come to know which rule is to be applied hold- next during the process of reaching for a solution to problem.

Control strategies help to overcome the abnormal situations, when there are more than one rules or fewer than one rule will have its left side match the current state.

A good control strategy must have the following requirements (characteristics).

• It should cause motion: A control strategy should always cause motion as only Shady such control strategy can lead to solution. If there is no motion that means there is no change of state and if state is not changed, then one will never proceed from the initial state. So reaching to a goal state will become a dream or impossible.

 For example, in water jug problem if one chooses first rule every time i.e., fill the 4-gallon jug full then one would never solve the problem.

One would continue indefinitely filling the 4-gallon jug with water.

So a control strategy should always cause motion.

• It should be systematic: A control strategy that causes motion but is not systematic is also not good. As in this type of strategy one can reach to a solution but it may pass from one state many times or many explore a particular sequence of operators several times unnecessarily and may use many more steps than are necessary.

The requirement that a control strategy be systematic corresponds to the need for global motion (over the course of several steps) as well as for local motion (over the course of a single step).

Some widely used control strategies are -

1) Breadth-first search                   

2) Depth-first search

3) Generate-and-test                     

4) Hill-climbing

5) Best-first search                         

6) Problem reduction

7) Constraint satisfaction               

8) Mean-end analysis