Implementing and Testing Expressive Description Logics

The aim of the crack project is the research and the development of a knowledge representation architecture based on description logic. The CRACK system is different from other knowledge representation systems for the high expressivity of the language and the possibility of having sound and complete reasoning procedures. With respect to other systems available in the research community, CRACK is more expressive, it is expandable to new constructs, it treats the conceptual and individual levels in a homogeneous way, it is modular, and it is comparably fast. However, CRACK algorithms are not optimal in the worst cases, e.g. in some (arguably rare in practice) worst cases they may require exponential memory. The performance of the system has been tested against several different classes of random knowledge bases, characterized by an order parameter generating phase transitions in the satisfiability probability space