System for ensuring the internal consistency of a fact repository

Methods and systems for maintaining the internal consistency of a fact repository are described. Accessed objects are checked for attribute-value pairs that have links to other objects. For any link to an object, the name of the linked-to object is inserted into the attribute-value pair having the link. The accessed objects are filtered to remove attribute-value pairs meeting predefined criteria, possibly resulting in null objects. Links to null objects are identified and removed.