Search strategy-artificial intelligence:

Soundness:

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.