Classic Family of Knowledge Representation Systems

Peter F. Patel-Schneider's team in Bell Labs has a knowledge representation/ontology tool called Classic and NeoClassic that is freely available for non-commercial use. Two Classic systems, one written in LISP and one written in C++, are available from Lucent. Non-commercial use requires only the signing of a simple license. Commercial use requires negotaion with Lucent.

Classic is a family of knowledge representation (KR) systems designed for applications where only limited expressive power is necessary, but rapid responses to questions are essential. The Classic systems are based on description logics (DLs), which gives them an object-centered flavor, and thus most of the features available in semantic networks are also available in Classic. Classic has a framework that allows users to represent descriptions, concepts, roles, individuals and rules. Classic allows for both primitive concepts, similar to the classes and frames of other knowledge representation systems and object-oriented programming languages, and defined concepts, i.e. concepts that have both necessary and sufficient conditions for membership. Concepts are automatically organized into a generalization taxonomy and objects are automatically made instances of all concepts for which they pass the membership test. Another type of reasoning that Classic does is to detect inconsistencies in information that it is told. In the presence of defined concepts these operations are non-trivial and useful.