(adj.,of a logic
or inference system) Not
monotonic
. Non-monotonic formalisms have been
proposed and used in AI and various applications. Examples of
nonmonotonic inferences include
default reasoning
, where
one assumes a 'normal' general truth unless it is contradicted by
more particular information (birds normally fly, but penguins
don't fly);
negation-by-failure
, commonly assumed in logic
programming systems, where one concludes, from a failure to prove a
proposition, that the proposition is false; and
implicit
closed-world assumptions
, often assumed in database
applications, where one concludes from a lack of information about
an entity in some corpus that the information is false (e.g. that
if someone is not listed in an employee database, that he or she is not
an employee.)