Structured Cases in CBR — Re-using and Adapting Cases for Time-tabling Problems

Abstract

In this paper, we present a case-based reasoning (CBR) approach for solving educational time-tabling problems. Following the basic idea behind CBR, the timetables from previously solved problems are employed to aid in the generation of solutions for new time-tabling problems. A list of feature-value pairs is insufficient to represent all the necessary information. We show that attribute graphs can be used to represent information such as the relations between events and thus can help to retrieve re-usable cases that have similar structures to the new problems. The case base is organised as a decision tree that stores the attribute graphs of previously solved time-tabling problems hierarchically. A new problem is classified to a node in the tree and all the cases stored below that node are retrieved for re-use. An example is given to illustrate the retrieval, re-use and adaptation of structured cases. The results from our experiments show the effectiveness of the retrieval and adaptation in the proposed method.