8. The user preference search system of claim 6 , wherein the look-up association is determined from a search history.
6. A user preference search system for searching a knowledge base to find a match answer and an alternative answer for a search term, comprising: a search engine stored on a computer system, comprising a processing unit, that performs a first search at a first location in the knowledge base and returns a match answer, and performs a second search at a second location in the knowledge base to find an alternative answer, wherein the alternative answer belongs to an alternative answer category determined by inputting a look-up association into an alternative answer probability table, wherein the look-up association is based on a search history table; and a table update system that updates the alternative answer probability table based on a table of previously determined category answer associations.