A knowledge representation (KR) language using constraints programming technique is considered. Each knowledge base structuring scheme has merits and demerits, each should be applied for the purpose it best serves, the prime focus being on creating well-grained and efficient KR. The use of the object-oriented approach makes it possible to unify various means of KR such as frames, semantic networks, and production rules as well as methods of constraint programming within the framework of one language. In this paper issues related to representation and reasoning with defaults and constraints in the EHCPRs system and its suitable implementation are taken up.
Keywords: extended hierarchical censored production rule, EHCPR, knowledge representation, natural kinds, defaults, constraints programming, object-oriented programming, frames, semantic networks, production rules