Conceptual dependency theory is a model of natural language understanding used in artificial intelligence systems.
Roger Schank at Stanford University introduced the model in 1969, in the early days of artificial intelligence.
[1] This model was extensively used by Schank's students at Yale University such as Robert Wilensky, Wendy Lehnert, and Janet Kolodner.
Schank developed the model to represent knowledge for natural language input into computers.
[2] The model uses the following basic representational tokens:[3] A set of conceptual transitions then act on this representation, e.g. an ATRANS is used to represent a transfer such as "give" or "take" while a PTRANS is used to act on locations such as "move" or "go".