70 Chapter 3 DevelopingKnowleDge-BaseDsystems 6. It should be an independent lower-level component so that it can be reused in other places. Also, it should be noted that no more than required knowledge is avail- able in a knowledge representation strategy. Depending on the type of knowledge, the representation scheme can be finalized. The knowledge representation scheme can be classified into two broad categories: (i) factual knowledge representation and (ii) procedural knowledge representation. The following sections describe factual knowl- edge and procedural knowledge in detail. 3.12 factual KNowledge Factual knowledge is also known as formal knowledge and can be re- presented using first-order logic supporting constants, variables, functions, and predicates. It also uses symbols such as And (), Or (), Not (~), Implies (), There exists (), For all (), and so on to make meaningful compound statements.