Fikes, R., & Hendrix, G. G. (1977). A network-based knowledge representation and its natural deduction system. SRI INTERNATIONAL MENLO PARK CA.
We describe a knowledge representation scheme called K-NET and a problem solving system called SNIFFER designed to answer queries using a K-NET knowledge base. K-NET uses a partitioned semantic net to combine the expressive capabilities of the first-order predicate calculus with linkage to procedural knowledge and with full indexing of objects to the relationships in which they participate. Facilities are also included for representing taxonomies of sets and for maintaining hierarchies of contexts. SNIFFER is a manager and coordinator of deductive and problem-solving processes. The basic system includes a logically complete set of natural deduction facilities that do not require statements to be converted into clause or prenex normal form. Using SNIFFER?s coroutine-based control structure, alternative proofs may be constructed in pseudo-parallel and results shared among them. In addition, SNIFFER can also manage application of specialist procedures that have specific knowledge about a particular domain or about the topology of the K-NET structures. For example, specialist procedures are used to manipulate taxonomic information and to link the system to information in external data bases.