The Free On-line Dictionary of Computing (30 December 2018):

production system

    A production system consists of a collection of
   productions (rules), a working memory of facts and an
   algorithm, known as forward chaining, for producing new
   facts from old.  A rule becomes eligible to "fire" when its
   conditions match some set of elements currently in working
   memory.  A conflict resolution strategy determines which of
   several eligible rules (the conflict set) fires next.  A
   condition is a list of symbols which represent constants,
   which must be matched exactly; variables which bind to the
   thing they match and "<> symbol" which matches a field not
   equal to symbol.

   Example production systems are OPS5, CLIPS, flex.

   (2005-06-17)