Representing Knowledge Gaps Effectively

In knowledge acquisition, one typically encounters two difficult situations: First, there are times when the system requests information that, due to a lack of information, the user is not in a position to provide at the level of precision requested. Second, there are situations where the system cannot capture information at the level of precision the user wishes to provide. We describe the techniques that have been developed for CYC to address these two cases during the extension of a variety of domains.