Paul Compton developed ripple-down rules are a way of representing knowledge so that it is easy to maintain. There is a variety of software that implements ripple-down rules, including a system that embeds RDR's within a machine learning toolkit
Publications
Srinivasan, A., Compton, P., Malor, R., Edwards, G., Sammut, C. and Lazarus, L. (1991). Knowledge Acquisition in Context for a Complex Domain. Proceedings of the European Knowledge Acquisition Workshop, Aberdeen.
Mansuri, Y., Kim, J-G., Compton, P. and Sammut, C. (1991). An evaluation of Ripple-Down Rules. Proceedings of the IJCAI'91 Knowledge Acquisition Workshop, Pokolbin, pp. 114-132.