  Static analysis by abstract interpretation is generally designed to be
''sound'', that is, it should not claim to establish properties that do not
hold-in other words, not provide ''false negatives'' about possible bugs. A
rarer requirement is that it should be ''complete'', meaning that it should be
able to infer certain properties if they hold. This paper describes a number of
practical issues and questions related to completeness that I have come across
over the years.
