Basics about Search

  1. Why are Searching and Searching algorithms important in AI?

The operation of an AI system can be characterised as a search process in which rules are tried until some sequence is found that produces the desired solution. While selecting a sequence of operations to determine an exact solution of a problem, an AI system has to face a large number of alternatives all of which are not at all equally promising for achieving the solution. Individual evaluation of all these alternatives even with the fastest available computer requires very long time which may exceed the entire lifetime of a human being depending on the complexity of the problem.

2. What is a Search Space?

A node is a discrete point and possible goal in the solution path. The set of all nodes is the search space

3. What are Blind Searches? Why do we need to know about blind searches?

A blind search (also called an uninformed search) is a search that has no information about its domain. The only capability of blind search is its ability to distinguish a non-goal state from the goal state. Blind searches have no preferences as to which nodes it should explore first. Examples of uninformed searches are Breadth First Search and Depth First Search.

One needs to know about uninformed search as they form the basis for some of the intelligent searches.

4. What is a Heuristic?

A heuristic is the approximation done to reduce the search space.  A heuristic function defines a state in terms of a number and this number is used for decision making in the search problems.

Heuristics are used when

  • The solution path for the problem is not known
  • The perfect solution is not computationally feasible

In Best First Search algorithm, the heuristic used is the distance of the node from the goal node

5. List some applications of Heuristic search

The application of Heuristic Search fall into three general classes

  • Path finding problems
  • Two player games
  • Constraint Satisfaction problem                                                                                                                                                                                                                              6.  What is an Informed Search?

Informed Search is a heuristic search in which there is a domain specific knowledge of the search. The heuristics are used in informed search to reduce the search space. Some of the informed searches are Best First Search and Hill Climbing.



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