What's Inheritance got to do with Knowledge Representation

Inheritance is the major or only inference mechanism in many hierarchical knowledge representation systems, such as most semantic networks and frame-based representation systems. These systems have suffered from the procedural aspects of the inheritance mechanism that they employed. Recent work on formalisms for inheritance has provided a better semantic footing for inheritance, overcoming these problems. However, inheritance is weak-both expressively and deductively; hierarchical representation systems need more expressive power and more deductive power than is provided by inheritance.