一些问题是有直接的解决方案的，我们可以应用公式或者遵照一个标准的流程来解决。而一些更有趣的问题没有这样的解决方案，通常需要search来解决。

Definition

A search problem is defined by a search space and a goal condition.

A search space is set of objects among which we search for the solution. 搜索空间是指问题中所有可能的状态或解决方案的集合；
A goal condition means the characteristics of the object we want to find in the search space. 目标条件用来描述我们在搜索空间中寻找的目标的特征。

Search(process) is the process of exploration of the search space.

The efficiency of the search depends on:

  • The search space and its size;
  • Method used to explore the search space;
  • Condition to test the satisfaction of the search objective.

Formulation of a search problem

Graph search problem

A search problem can be often represented with a graph where:

TODO…

Search methods