Are there individual concepts? Proper names and individual concepts in SI-Nets

We discuss some aspects of the role played by descriptional knowledge in expressions denoting individual objects. In knowledge representation systems such as KL-ONE and KRYPTON which use semantic networks to express descriptional information, the problem is to establish whether the use of individual concepts in a network is justified. In the light of theoretical and applicational considerations, in the proposed solution only definite descriptions are considered as being characterizable by means of definitions. Vice versa, proper names, in the strict sense, will be treated as having no definitional dimension, and as such only appear in the assertional knowledge base. A description is given of how this solution was realized in PROCNE , a knowledge representation tool in which logic representation and structured inheritance semantic nets (SI-Nets) are combined.