Search strategy-artificial intelligence:
You can hear in some application domains - i.e. automated theorem proving - that a search is "sound and complete". Soundness in theorem proving means that the search to find a evidence will not succeed if you give it a wrong theorem to prove. In general, this extends to searching, where a search is unsound if it search a solution to a problem with no solution. This kind of unsound search cannot be the end of the world if you are only interested in using it for problems where you know there is a solution (and it performs well in finding this kind of solutions). Another kind of unsound search is when a search finds the wrong solution to a problem. It is more worrying and the problem will probably lie with the goal testing method.
Additional Knowledge in Search
The amount of extra knowledge available to your agent will affect how it performs. In the following sections of this chapter, we will look at uninformed search strategy, where no additional knowledge is given, and heuristic searches, where any information about the goal, intermediate states and operators may be used to improve the efficiency of the search strategy.