GC: n
CT: In the context of computer and information sciences, an ontology defines a set of representational primitives with which to model a domain of knowledge or discourse. The representational primitives are typically classes (or sets), attributes (or properties), and relationships (or relations among class members). The definitions of the representational primitives include information about their meaning and constraints on their logically consistent application. In the context of database systems, ontology can be viewed as a level of abstraction of data models, analogous to hierarchical and relational models, but intended for modeling knowledge about individuals, their attributes, and their relationships to other individuals. Ontologies are typically specified in languages that allow abstraction away from data structures and implementation strategies; in practice, the languages of ontologies are closer in expressive power to first-order logic than languages used to model databases. For this reason, ontologies are said to be at the “semantic” level, whereas database schema are models of data at the “logical” or “physical” level. Due to their independence from lower level data models, ontologies are used for integrating heterogeneous databases, enabling interoperability among disparate systems, and specifying interfaces to independent, knowledge-based services. In the technology stack of the Semantic Web standards, ontologies are called out as an explicit layer. There are now standard languages and a variety of commercial and open source tools for creating and working with ontologies.
S: http://tomgruber.org/writing/ontology-definition-2007.htm (last access: 21 December 2014)
N: 1. “metaphysical science or study of being,” 1660s (Gideon Harvey), from Modern Latin ontologia (c.1600), from onto- (word-forming element meaning “a being, individual; being, existence,” from Greek onto-, from stem of on (genitive ontos) “being,” neuter present participle of einai “to be”) + -logy (word-forming element meaning “a speaking, discourse, treatise, doctrine, theory, science,” from Greek -logia (often via French -logie or Medieval Latin -logia), from root of legein “to speak;” thus, “the character or deportment of one who speaks or treats of (a certain subject);”).
2. The term “ontology” comes from the field of philosophy that is concerned with the study of being or existence. In philosophy, one can talk about an ontology as a theory of the nature of existence (e.g., Aristotle’s ontology offers primitive categories, such as substance and quality, which were presumed to account for All That Is). In computer and information science, ontology is a technical term denoting an artifact that is designed for a purpose, which is to enable the modeling of knowledge about some domain, real or imagined.
The term had been adopted by early Artificial Intelligence (AI) researchers, who recognized the applicability of the work from mathematical logic and argued that AI researchers could create new ontologies as computational models that enable certain kinds of automated reasoning. In the 1980’s the AI community came to use the term ontology to refer to both a theory of a modeled world (e.g., a Naïve Physics) and a component of knowledge systems. Some researchers, drawing inspiration from philosophical ontologies, viewed computational ontology as a kind of applied philosophy.
In the early 1990’s, an effort to create interoperability standards identified a technology stack that called out the ontology layer as a standard component of knowledge systems.
3. (A collection) of statements written in a language such as RDF (resource description framework) that define the relations between concepts and specify logical rules for reasoning about them.
4. Computers will “understand” the meaning of semantic data on a web page by following links to specified ontologies.
S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=ontology&searchmode=none (last access: 21 December 2014). 2. http://tomgruber.org/writing/ontology-definition-2007.htm (last access: 21 December 2014). 3 & 4. TERMIUMPLUS.
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CR: artificial intelligence, computational intelligence, computer science, semantic network, Semantic Web.
