Concepts

Abstract

A concept is an entity of consciousness. We know a concept when we encounter one “in action”, because it exceeds its stand-in descriptive label as a word, phrase or sentence. A concept might be a directly conceived or an intuited object of thought. In general, every object, issue, idea, person, process, place, etc., can generate a concept. Although concepts are an integral part of human cognition (or perhaps precisely because of this fact), their exact definition is fairly difficult. Various viewpoints and approaches to their explanation are presented in the first part of the present chapter. To be of any practical use for representing knowledge, concepts cannot appear in isolation, but must be associated with each other. Thus, in the continuation of the chapter, the most important formalisms for organizing concepts are presented along with the examples of organizations in actual applications. The main practical application of concepts is document retrieval based on the actual meaning referred to with the search phrase instead of the one based on (more or less) literal phrase matching. The last section of the chapter is dedicated to the topics related to concept-based search.