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

knowledge representation
KR

   The subfield of artificial intelligence concerned with
   designing and using systems for storing knowledge - facts
   and rules about some subject.

   A body of formally represented knowledge is based on a
   conceptualisation - an abstract view of the world that we
   wish to represent.  In order to manipulate this knowledge we
   must specify how the abstract conceptualisation is represented
   as a concrete data structure.  An ontology is an explicit
   specification of a conceptualisation.

   (1994-10-19)