Yamaguchi, YasushiKimura, FumihikoTen Hagen, Paul J. W.2015-10-052015-10-0519871017-4656https://doi.org/10.2312/egtp.19871040User friendliness is one of the unresolved problems in CAD systems. There are many possible directions for improving user friendliness. Understanding of the modeling process is one of the most important directions. It is natural for a user to describe the model in terms of its evolution. We call this concept model derivation. To construct and use model derivation, we propose a history mechanism which keeps and manipulates the history of the modeling process. The history mechanism manages high level interactions by introducing powerful symbolic computation to manipulate the history. Since the history representation is based on the operation's syntax and separated from the internal model representation, it is easy to apply the history mechanism to any modeling system which uses established techniques. Thus the system designer can easily introduce model derivation without reducing efficiency of the implementation.10.2312/egtp.19871040