ABSTRACT
There have been two major developments related to the NETL system since this chapter was written. First, David Touretzky completed a PhD thesis at Carnegie-Mellon University in which he was able to develop a sound logical framework for NETL-like knowledge-representation systems with multiple inheritance and exceptions (Touretzky, 1986). The inheritance scheme used in the original NETL system was adequate for simple situations, but it produced some counter-intuitive and inconsistent results in more complex cases.
