Handling Incomplete or Uncertain Data and Vague Queries in Database Applications

摘要: One often has to handle data that are far from precise and certain. In fact, the value of an attribute object may be completely unknown, incompletely known (i.e., only a subset possible values is known), or uncertain (e.g., probability possibility distribution for its known). addition, not applicable some objects being considered and, in certain cases, we know whether even exists, it simply known.