computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to practical disciplines (includin ...

and

information science Information science (also known as information studies) is an academic field which is primarily concerned with analysis, collection, classification, manipulation, storage, retrieval, movement, dissemination, and protection of information. ...

, an ontology encompasses a representation, formal naming, and definition of the categories, properties, and relations between the concepts, data, and entities that substantiate one, many, or all domains of discourse. More simply, an ontology is a way of showing the properties of a subject area and how they are related, by defining a set of concepts and categories that represent the subject. Every

academic discipline An academy (Attic Greek: Ἀκαδήμεια; Koine Greek Ἀκαδημία) is an institution of secondary or tertiary higher learning (and generally also research or honorary membership). The name traces back to Plato's school of philosophy ...

or field creates ontologies to limit complexity and organize data into information and knowledge. Each uses ontological assumptions to frame explicit theories, research and applications. New ontologies may improve problem solving within that domain. Translating research papers within every field is a problem made easier when experts from different countries maintain a

controlled vocabulary Control may refer to: Basic meanings Economics and business * Control (management), an element of management * Control, an element of management accounting * Comptroller (or controller), a senior financial officer in an organization * Controllin ...

jargon Jargon is the specialized terminology associated with a particular field or area of activity. Jargon is normally employed in a particular communicative context and may not be well understood outside that context. The context is usually a partic ...

between each of their languages. For instance, the definition and ontology of economics is a primary concern in

Marxist economics Marxian economics, or the Marxian school of economics, is a heterodox school of political economic thought. Its foundations can be traced back to Karl Marx's critique of political economy. However, unlike critics of political economy, Marxian e ...

, but also in other subfields of economics. An example of economics relying on information science occurs in cases where a simulation or model is intended to enable economic decisions, such as determining what

capital asset A capital asset is defined as property of any kind held by an assessee, whether connected with their business or profession or not connected with their business or profession. It includes all kinds of property, movable or immovable, tangible or in ...

s are at risk and by how much (see risk management). What ontologies in both

and

philosophy Philosophy (from , ) is the systematized study of general and fundamental questions, such as those about existence, reason, knowledge, values, mind, and language. Such questions are often posed as problems to be studied or resolved. S ...

have in common is the attempt to represent entities, ideas and events, with all their interdependent properties and relations, according to a system of categories. In both fields, there is considerable work on problems of

ontology engineering In computer science, information science and systems engineering, ontology engineering is a field which studies the methods and methodologies for building ontologies, which encompasses a representation, formal naming and definition of the categor ...

(e.g.,

Quine Quine may refer to: * Quine (surname), people with the surname ''Quine'' * Willard Van Orman Quine, the philosopher, or things named after him: ** Quine (computing), a program that produces its source code as output ** Quine–McCluskey algorithm ...

and Kripke in philosophy,

Sowa The SoWa Art & Design District (South of Washington) in the South End of Boston, Massachusetts, USA, is a community of artist studios, contemporary art galleries, boutiques, design showrooms, and restaurants. Once an area of neglected warehou ...

and Guarino in computer science), and debates concerning to what extent

normative Normative generally means relating to an evaluative standard. Normativity is the phenomenon in human societies of designating some actions or outcomes as good, desirable, or permissible, and others as bad, undesirable, or impermissible. A norm in ...

ontology is possible (e.g.,

foundationalism Foundationalism concerns philosophical theories of knowledge resting upon non-inferential justified belief, or some secure foundation of certainty such as a conclusion inferred from a basis of sound premises.Simon Blackburn, ''The Oxford Dictio ...

and

coherentism In philosophical epistemology, there are two types of coherentism: the coherence theory of truth; and the coherence theory of justification (also known as epistemic coherentism). Coherent truth is divided between an anthropological approach, wh ...

in philosophy, BFO and Cyc in artificial intelligence).

Applied ontology Applied ontology involves the practical application of ontological resources to specific domains, such as management, relationships, biomedicine, information science or geography. Much work in applied ontology is carried out within the framewo ...

is considered a successor to prior work in philosophy, however many current efforts are more concerned with establishing

controlled vocabularies Control may refer to: Basic meanings Economics and business * Control (management), an element of management * Control, an element of management accounting * Comptroller (or controller), a senior financial officer in an organization * Controlling ...

of narrow domains than

first principles In philosophy and science, a first principle is a basic proposition or assumption that cannot be deduced from any other proposition or assumption. First principles in philosophy are from First Cause attitudes and taught by Aristotelians, and nua ...

, the existence of fixed essences or whether enduring objects (e.g.,

perdurantism Perdurantism or perdurance theory is a philosophical theory of persistence and identity.Temporal parts

and

endurantism Endurantism or endurance theory is a philosophical theory of persistence and identity. According to the endurantist view, material objects are persisting three-dimensional individuals wholly present at every moment of their existence, which goes ...

) may be ontologically more primary than

process A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management * Business process, activities that produce a specific s ...

es.

Artificial intelligence Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech r ...

has retained the most attention regarding

applied ontology Applied ontology involves the practical application of ontological resources to specific domains, such as management, relationships, biomedicine, information science or geography. Much work in applied ontology is carried out within the framewo ...

in subfields like

natural language processing Natural language processing (NLP) is an interdisciplinary subfield of linguistics, computer science, and artificial intelligence concerned with the interactions between computers and human language, in particular how to program computers to pr ...

within

machine translation Machine translation, sometimes referred to by the abbreviation MT (not to be confused with computer-aided translation, machine-aided human translation or interactive translation), is a sub-field of computational linguistics that investigates th ...

and

knowledge representation Knowledge representation and reasoning (KRR, KR&R, KR²) is the field of artificial intelligence (AI) dedicated to representing information about the world in a form that a computer system can use to solve complex tasks such as diagnosing a medi ...

, but ontology editors are being used often in a range of fields like education without the intent to contribute to AI.

Etymology

The

compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fortified with defensive struct ...

word ''ontology'' combines ''

onto In mathematics, a surjective function (also known as surjection, or onto function) is a function that every element can be mapped from element so that . In other words, every element of the function's codomain is the image of one element of i ...

-'', from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

ὄν, ''on'' ( gen. ὄντος, ''ontos''), i.e. "being; that which is", which is the

present The present (or here'' and ''now) is the time that is associated with the events perceived directly and in the first time, not as a recollection (perceived more than once) or a speculation (predicted, hypothesis, uncertain). It is a period o ...

participle In linguistics, a participle () (from Latin ' a "sharing, partaking") is a nonfinite verb form that has some of the characteristics and functions of both verbs and adjectives. More narrowly, ''participle'' has been defined as "a word derived from ...

of the

verb A verb () is a word (part of speech) that in syntax generally conveys an action (''bring'', ''read'', ''walk'', ''run'', ''learn''), an occurrence (''happen'', ''become''), or a state of being (''be'', ''exist'', ''stand''). In the usual descrip ...

εἰμί, ''eimí'', i.e. "to be, I am", and -λογία, ''

-logia ''-logy'' is a suffix in the English language, used with words originally adapted from Ancient Greek ending in ('). The earliest English examples were anglicizations of the French '' -logie'', which was in turn inherited from the Latin '' -lo ...

'', i.e. "logical discourse", see

classical compound Neoclassical compounds are compound words composed from combining forms (which act as affixes or stems) derived from classical Latin or ancient Greek roots. New Latin comprises many such words and is a substantial component of the technical a ...

s for this type of word formation. While the

etymology Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the Phonological chan ...

is Greek, the oldest extant record of the word itself, the

New Latin New Latin (also called Neo-Latin or Modern Latin) is the revival of Literary Latin used in original, scholarly, and scientific works since about 1500. Modern scholarly and technical nomenclature, such as in zoological and botanical taxonomy ...

form ''ontologia'', appeared in 1606 in the work ''

Ogdoas Scholastica Jacob Lorhard ( la, Jacobus Lorhardus; 1561 – 19 May 1609) was a German philosopher and pedagogue based in St. Gallen, Switzerland. Biography Lorhard was born in Münsingen, in the Duchy of Württemberg. He studied at the University of ...

'' by

Jacob Lorhard Jacob Lorhard ( la, Jacobus Lorhardus; 1561 – 19 May 1609) was a German philosopher and pedagogue based in St. Gallen, Switzerland. Biography Lorhard was born in Münsingen, in the Duchy of Württemberg. He studied at the University of ...

(''Lorhardus'') and in 1613 in the '' Lexicon philosophicum'' by Rudolf Göckel (''Goclenius''). The first occurrence in English of ''ontology'' as recorded by the ''OED'' (''

Oxford English Dictionary The ''Oxford English Dictionary'' (''OED'') is the first and foundational historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a co ...

'', online edition, 2008) came in '' Archeologia Philosophica Nova'' or ''New Principles of Philosophy'' by Gideon Harvey.

History

Ontologies arise out of the branch of

known as

metaphysics Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of consci ...

, which deals with questions like "what exists?" and "what is the nature of reality?". One of five traditional branches of philosophy, metaphysics is concerned with exploring existence through properties, entities and relations such as those between

particular In metaphysics, particulars or individuals are usually contrasted with universals. Universals concern features that can be exemplified by various different particulars. Particulars are often seen as concrete, spatiotemporal entities as opposed to a ...

s and

universals In metaphysics, a universal is what particular things have in common, namely characteristics or qualities. In other words, universals are repeatable or recurrent entities that can be instantiated or exemplified by many particular things. For ex ...

intrinsic and extrinsic properties In science and engineering, an intrinsic property is a property of a specified subject that exists itself or within the subject. An extrinsic property is not essential or inherent to the subject that is being characterized. For example, m ...

, or

essence Essence ( la, essentia) is a polysemic term, used in philosophy and theology as a designation for the property or set of properties that make an entity or substance what it fundamentally is, and which it has by necessity, and without which it ...

and

existence Existence is the ability of an entity to interact with reality. In philosophy, it refers to the ontological property of being. Etymology The term ''existence'' comes from Old French ''existence'', from Medieval Latin ''existentia/exsistentia ...

. Metaphysics has been an ongoing topic of discussion since recorded history. Since the mid-1970s, researchers in the field of

artificial intelligence Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech r ...

(AI) have recognized that

knowledge engineering Knowledge engineering (KE) refers to all technical, scientific and social aspects involved in building, maintaining and using knowledge-based systems. Background Expert systems One of the first examples of an expert system was MYCIN, an appl ...

is the key to building large and powerful AI systems. AI researchers argued that they could create new ontologies as

computational model A computational model uses computer programs to simulate and study complex systems using an algorithmic or mechanistic approach and is widely used in a diverse range of fields spanning from physics, chemistry and biology to economics, psychology, ...

s that enable certain kinds of

automated reasoning In computer science, in particular in knowledge representation and reasoning and metalogic, the area of automated reasoning is dedicated to understanding different aspects of reasoning. The study of automated reasoning helps produce computer pro ...

, which was only marginally successful. In the 1980s, the AI community began to use the term ''ontology'' to refer to both a theory of a modeled world and a component of

knowledge-based systems A knowledge-based system (KBS) is a computer program that reasons and uses a knowledge base to solve complex problems. The term is broad and refers to many different kinds of systems. The one common theme that unites all knowledge based systems i ...

. In particular, David Powers introduced the word ''ontology'' to AI to refer to real world or robotic grounding, publishing in 1990 literature reviews emphasizing grounded ontology in association with the call for papers for a AAAI Summer Symposium Machine Learning of Natural Language and Ontology, with an expanded version published in SIGART Bulletin and included as a preface to the proceedings. Some researchers, drawing inspiration from philosophical ontologies, viewed computational ontology as a kind of applied philosophy. In 1993, the widely cited web page and paper "Toward Principles for the Design of Ontologies Used for Knowledge Sharing" by Tom Gruber used ''ontology'' as a technical term in

closely related to earlier idea of semantic networks and taxonomies. Gruber introduced the term as ''a specification of a conceptualization'':

An ontology is a description (like a formal specification of a program) of the concepts and relationships that can formally exist for an agent or a community of agents. This definition is consistent with the usage of ontology as set of concept definitions, but more general. And it is a different sense of the word than its use in philosophy.

Attempting to distance ontologies from taxonomies and similar efforts in

knowledge modeling Knowledge modeling is a process of creating a computer interpretable model of knowledge or standard specifications about a kind of process and/or about a kind of facility or product. The resulting knowledge model can only be computer interpretable ...

that rely on classes and

inheritance Inheritance is the practice of receiving private property, titles, debts, entitlements, privileges, rights, and obligations upon the death of an individual. The rules of inheritance differ among societies and have changed over time. Offi ...

, Gruber stated (1993):

Ontologies are often equated with taxonomic hierarchies of classes, class definitions, and the subsumption relation, but ontologies need not be limited to these forms. Ontologies are also not limited to conservative definitions — that is, definitions in the traditional logic sense that only introduce terminology and do not add any knowledge about the world. To specify a conceptualization, one needs to state
axiom An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or f ...
s that do constrain the possible interpretations for the defined terms.

As refinement of Gruber's definition Feilmayr and Wöß (2016) stated: "An ontology is a formal, explicit specification of a shared conceptualization that is characterized by high semantic expressiveness required for increased complexity."

Components

Contemporary ontologies share many structural similarities, regardless of the language in which they are expressed. Most ontologies describe individuals (instances), classes (concepts), attributes and relations. In this section each of these components is discussed in turn. Common components of ontologies include: ; Individuals : Instances or objects (the basic or "ground level" objects) ; Classes : Sets, collections, concepts, classes in programming, types of objects or kinds of things ;

Attributes Attribute may refer to: * Attribute (philosophy), an extrinsic property of an object * Attribute (research), a characteristic of an object * Grammatical modifier, in natural languages * Attribute (computing), a specification that defines a proper ...

: Aspects, properties, features, characteristics or parameters that objects (and classes) can have ; Relations : Ways in which classes and individuals can be related to one another ; Function terms : Complex structures formed from certain relations that can be used in place of an individual term in a statement ; Restrictions : Formally stated descriptions of what must be true in order for some assertion to be accepted as input ; Rules : Statements in the form of an if-then (antecedent-consequent) sentence that describe the logical inferences that can be drawn from an assertion in a particular form ; Axioms : Assertions (including rules) in a

logical form In logic, logical form of a statement is a precisely-specified semantic version of that statement in a formal system. Informally, the logical form attempts to formalize a possibly ambiguous statement into a statement with a precise, unambi ...

that together comprise the overall theory that the ontology describes in its domain of application. This definition differs from that of "axioms" in

generative grammar Generative grammar, or generativism , is a linguistic theory that regards linguistics as the study of a hypothesised innate grammatical structure. It is a biological or biologistic modification of earlier structuralist theories of linguisti ...

and

formal logic Logic is the study of correct reasoning. It includes both Mathematical logic, formal and informal logic. Formal logic is the science of Validity (logic), deductively valid inferences or of logical truths. It is a formal science investigating h ...

. In those disciplines, axioms include only statements asserted as ''a priori'' knowledge. As used here, "axioms" also include the theory derived from axiomatic statements ; Events : The changing of attributes or relations Ontologies are commonly encoded using

ontology language In computer science and artificial intelligence, ontology languages are formal languages used to construct ontologies. They allow the encoding of knowledge about specific domains and often include reasoning rules that support the processing of t ...

Types

Domain ontology

A domain ontology (or domain-specific ontology) represents concepts which belong to a realm of the world, such as biology or politics. Each domain ontology typically models domain-specific definitions of terms. For example, the word ''

card Card or The Card may refer to: * Various types of plastic cards: **By type ***Magnetic stripe card ***Chip card ***Digital card **By function ***Payment card ****Credit card ****Debit card **** EC-card **** Identity card ****European Health Insuran ...

'' has many different meanings. An ontology about the domain of

poker Poker is a family of Card_game#Comparing_games, comparing card games in which Card player, players betting (poker), wager over which poker hand, hand is best according to that specific game's rules. It is played worldwide, however in some plac ...

would model the "

playing card A playing card is a piece of specially prepared card stock, heavy paper, thin cardboard, plastic-coated paper, cotton-paper blend, or thin plastic that is marked with distinguishing motifs. Often the front (face) and back of each card has a fi ...

" meaning of the word, while an ontology about the domain of

computer hardware Computer hardware includes the physical parts of a computer, such as the case, central processing unit (CPU), random access memory (RAM), monitor, mouse, keyboard, computer data storage, graphics card, sound card, speakers and motherboard. ...

would model the "

punched card A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to di ...

" and "

video card A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer moni ...

" meanings. Since domain ontologies are written by different people, they represent concepts in very specific and unique ways, and are often incompatible within the same project. As systems that rely on domain ontologies expand, they often need to merge domain ontologies by hand-tuning each entity or using a combination of software merging and hand-tuning. This presents a challenge to the ontology designer. Different ontologies in the same domain arise due to different languages, different intended usage of the ontologies, and different perceptions of the domain (based on cultural background, education, ideology, etc.). At present, merging ontologies that are not developed from a common

upper ontology In information science, an upper ontology (also known as a top-level ontology, upper model, or foundation ontology) is an ontology (in the sense used in information science) which consists of very general terms (such as "object", "property", "rel ...

is a largely manual process and therefore time-consuming and expensive. Domain ontologies that use the same upper ontology to provide a set of basic elements with which to specify the meanings of the domain ontology entities can be merged with less effort. There are studies on generalized techniques for merging ontologies, but this area of research is still ongoing, and it's a recent event to see the issue sidestepped by having multiple domain ontologies using the same upper ontology like the OBO Foundry.

Upper ontology

An upper ontology (or foundation ontology) is a model of the commonly shared relations and objects that are generally applicable across a wide range of domain ontologies. It usually employs a

core glossary A glossary (from grc, γλῶσσα, ''glossa''; language, speech, wording) also known as a vocabulary or clavis, is an alphabetical list of terms in a particular domain of knowledge with the definitions for those terms. Traditionally, a glos ...

that overarches the terms and associated object descriptions as they are used in various relevant domain ontologies. Standardized upper ontologies available for use include BFO, BORO method,

Dublin Core 220px, Logo image of DCMI, which formulates Dublin Core The Dublin Core, also known as the Dublin Core Metadata Element Set (DCMES), is a set of fifteen "core" elements (properties) for describing resources. This fifteen-element Dublin Core has ...

, GFO, Cyc,

SUMO is a form of competitive full-contact wrestling where a ''rikishi'' (wrestler) attempts to force his opponent out of a circular ring (''dohyō'') or into touching the ground with any body part other than the soles of his feet (usually by thr ...

UMBEL In botany, an umbel is an inflorescence that consists of a number of short flower stalks (called pedicels) that spread from a common point, somewhat like umbrella ribs. The word was coined in botanical usage in the 1590s, from Latin ''umbella'' " ...

, the Unified Foundational Ontology (UFO), and DOLCE.

WordNet WordNet is a lexical database of semantic relations between words in more than 200 languages. WordNet links words into semantic relations including synonyms, hyponyms, and meronyms. The synonyms are grouped into ''synsets'' with short definiti ...

has been considered an upper ontology by some and has been used as a linguistic tool for learning domain ontologies.

Hybrid ontology

The Gellish ontology is an example of a combination of an upper and a domain ontology.

Visualization

A survey of ontology visualization methods is presented by Katifori et al. An updated survey of ontology visualization methods and tools was published by Dudás et al. The most established ontology visualization methods, namely indented tree and graph visualization are evaluated by Fu et al. A visual language for ontologies represented in OWL is specified by the ''Visual Notation for OWL Ontologies (VOWL)''.

Engineering

Ontology engineering (also called ontology building) is a set of tasks related to the development of ontologies for a particular domain. It is a subfield of

that studies the ontology development process, the ontology life cycle, the methods and methodologies for building ontologies, and the tools and languages that support them. Ontology engineering aims to make explicit the knowledge contained in software applications, and organizational procedures for a particular domain. Ontology engineering offers a direction for overcoming semantic obstacles, such as those related to the definitions of business terms and software classes. Known challenges with ontology engineering include: # Ensuring the ontology is ''current'' with

domain knowledge Domain knowledge is knowledge of a specific, specialized discipline or field, in contrast to general (or domain-independent) knowledge. The term is often used in reference to a more general discipline—for example, in describing a software eng ...

and term use # Providing ''sufficient specificity and concept coverage'' for the domain of interest, thus minimizing the content completeness problem # Ensuring the ontology can support its use cases

Editors

Ontology editors are applications designed to assist in the creation or manipulation of ontologies. It is common for ontology editors to use one or more ontology languages. Aspects of ontology editors include: visual navigation possibilities within the knowledge model,

inference engine In the field of artificial intelligence, an inference engine is a component of the system that applies logical rules to the knowledge base to deduce new information. The first inference engines were components of expert systems. The typical expert ...

s and

information extraction Information extraction (IE) is the task of automatically extracting structured information from unstructured and/or semi-structured machine-readable documents and other electronically represented sources. In most of the cases this activity concer ...

; support for modules; the import and export of foreign

languages for ontology matching; and the support of meta-ontologies such as OWL-S,

, etc.

Learning

Ontology learning is the automatic or semi-automatic creation of ontologies, including extracting a domain's terms from natural language text. As building ontologies manually is extremely labor-intensive and time-consuming, there is great motivation to automate the process. Information extraction and

text mining Text mining, also referred to as ''text data mining'', similar to text analytics, is the process of deriving high-quality information from text. It involves "the discovery by computer of new, previously unknown information, by automatically extract ...

have been explored to automatically link ontologies to documents, for example in the context of the BioCreative challenges.

Research

Epistemological assumptions, which in research asks "What do you know? or "How do you know it?", creates the foundation researchers use when approaching a certain topic or area for potential research. As epistemology is directly linked to knowledge and how we come about accepting certain truths, individuals conducting academic research must understand what allows them to begin theory building. Simply, epistemological assumptions force researchers to question how they arrive at the knowledge they have.

Languages

is a

formal language In logic, mathematics, computer science, and linguistics, a formal language consists of words whose letters are taken from an alphabet and are well-formed according to a specific set of rules. The alphabet of a formal language consists of sym ...

used to encode an ontology. There are a number of such languages for ontologies, both proprietary and standards-based: * Common Algebraic Specification Language is a general logic-based specification language developed within the IFIP working group 1.3 "Foundations of System Specifications" and is a ''de facto'' standard language for software specifications. It is now being applied to ontology specifications in order to provide modularity and structuring mechanisms. *

Common logic Common Logic (CL) is a framework for a family of logic languages, based on first-order logic, intended to facilitate the exchange and transmission of knowledge in computer-based systems. The CL definition permits and encourages the developmen ...

is ISO standard 24707, a specification of a family of ontology languages that can be accurately translated into each other. * The Cyc project has its own ontology language called CycL, based on first-order predicate calculus with some higher-order extensions. *

DOGMA Dogma is a belief or set of beliefs that is accepted by the members of a group without being questioned or doubted. It may be in the form of an official system of principles or doctrines of a religion, such as Roman Catholicism, Judaism, Islam o ...

(Developing Ontology-Grounded Methods and Applications) adopts the fact-oriented modeling approach to provide a higher level of semantic stability. * The Gellish language includes rules for its own extension and thus integrates an ontology with an ontology language. *

IDEF5 IDEF5 (''Integrated Definition for Ontology Description Capture Method'') is a software engineering method to develop and maintain usable, accurate domain ontologies.Perakath C. Benjamin et al. (1994)''IDEF5 Method Report''. Knowledge Based Systems ...

is a

software engineering Software engineering is a systematic engineering approach to software development. A software engineer is a person who applies the principles of software engineering to design, develop, maintain, test, and evaluate computer software. The term '' ...

method to develop and maintain usable, accurate, domain ontologies. * KIF is a syntax for

first-order logic First-order logic—also known as predicate logic, quantificational logic, and first-order predicate calculus—is a collection of formal systems used in mathematics, philosophy, linguistics, and computer science. First-order logic uses quant ...

that is based on

S-expression In computer programming, an S-expression (or symbolic expression, abbreviated as sexpr or sexp) is an expression in a like-named notation for nested list (tree-structured) data. S-expressions were invented for and popularized by the programming la ...

s. SUO-KIF is a derivative version supporting the

Suggested Upper Merged Ontology The Suggested Upper Merged Ontology (SUMO) is an upper ontology intended as a foundation ontology for a variety of computer information processing systems. SUMO defines a hierarchy of ''classes'' and related rules and relationships. These are expre ...

. * MOF and UML are standards of the OMG * Olog is a category theoretic approach to ontologies, emphasizing translations between ontologies using

functor In mathematics, specifically category theory, a functor is a mapping between categories. Functors were first considered in algebraic topology, where algebraic objects (such as the fundamental group) are associated to topological spaces, and ma ...

s. *

OBO Obo is the capital of Haut-Mbomou, one of the 14 prefectures of the Central African Republic. It is close to the African Pole of Inaccessibility. Poste Airport is located near the town. History Obo was named after the local Zande chief O ...

, a language used for biological and biomedical ontologies. * OntoUML is an ontologically well-founded profile of UML for conceptual modeling of domain ontologies. * OWL is a language for making ontological statements, developed as a follow-on from RDF and

RDFS RDF Schema (Resource Description Framework Schema, variously abbreviated as RDFS, , RDF-S, or RDF/S) is a set of classes with certain properties using the RDF extensible knowledge representation data model, providing basic elements for the descr ...

, as well as earlier ontology language projects including

OIL An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

, DAML, and DAML+OIL. OWL is intended to be used over the

World Wide Web The World Wide Web (WWW), commonly known as the Web, is an information system enabling documents and other web resources to be accessed over the Internet. Documents and downloadable media are made available to the network through web ...

, and all its elements (classes, properties and individuals) are defined as RDF

resource Resource refers to all the materials available in our environment which are technologically accessible, economically feasible and culturally sustainable and help us to satisfy our needs and wants. Resources can broadly be classified upon their ...

s, and identified by

URI Uri may refer to: Places * Canton of Uri, a canton in Switzerland * Úri, a village and commune in Hungary * Uri, Iran, a village in East Azerbaijan Province * Uri, Jammu and Kashmir, a town in India * Uri (island), an island off Malakula Isla ...

s. * Rule Interchange Format (RIF) and F-Logic combine ontologies and rules. * Semantic Application Design Language (SADL) captures a subset of the expressiveness of OWL, using an English-like language entered via an

Eclipse An eclipse is an astronomical event that occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three ce ...

Plug-in. * SBVR (Semantics of Business Vocabularies and Rules) is an OMG standard adopted in industry to build ontologies. * TOVE Project, TOronto Virtual Enterprise project

Published examples

* Arabic Ontology, a linguistic ontology for Arabic, which can be used as an Arabic Wordnet but with ontologically-clean content. * AURUM - Information Security Ontology, An ontology for information security knowledge sharing, enabling users to collaboratively understand and extend the domain knowledge body. It may serve as a basis for automated information security risk and compliance management. * BabelNet, a very large multilingual semantic network and ontology, lexicalized in many languages * Basic Formal Ontology, a formal upper ontology designed to support scientific research * BioPAX, an ontology for the exchange and interoperability of biological pathway (cellular processes) data * BMO, an e-Business Model Ontology based on a review of enterprise ontologies and business model literature * SSBMO, a Strongly Sustainable Business Model Ontology based on a review of the systems based natural and social science literature (including business). Includes critique of and significant extensions to the Business Model Ontology (BMO). * CCO and GexKB, Application Ontologies (APO) that integrate diverse types of knowledge with the Cell Cycle Ontology (CCO) and the Gene Expression Knowledge Base (GexKB) * CContology (Customer Complaint Ontology), an e-business ontology to support online customer complaint management *

CIDOC Conceptual Reference Model The CIDOC Conceptual Reference Model (CRM) provides an extensible ontology for concepts and information in cultural heritage and museum documentation. It is the international standard ( ISO 21127:2014) for the controlled exchange of cultural he ...

, an ontology for

cultural heritage Cultural heritage is the heritage of tangible and intangible heritage assets of a group or society that is inherited from past generations. Not all heritages of past generations are "heritage"; rather, heritage is a product of selection by soc ...

* COSMO, a Foundation Ontology (current version in OWL) that is designed to contain representations of all of the primitive concepts needed to logically specify the meanings of any domain entity. It is intended to serve as a basic ontology that can be used to translate among the representations in other ontologies or databases. It started as a merger of the basic elements of the OpenCyc and SUMO ontologies, and has been supplemented with other ontology elements (types, relations) so as to include representations of all of the words in the Longman dictionary defining vocabulary. * Computer Science Ontology, an automatically generated ontology of research topics in the field of

Computer Science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to practical disciplines (includin ...

* Cyc, a large Foundation Ontology for formal representation of the universe of discourse * Disease Ontology, designed to facilitate the mapping of diseases and associated conditions to particular medical codes * DOLCE, a Descriptive Ontology for Linguistic and Cognitive Engineering * Drammar, ontology of drama *

, a simple ontology for documents and publishing * Financial Industry Business Ontology (FIBO), a business conceptual ontology for the financial industry * Foundational, Core and Linguistic Ontologies * Foundational Model of Anatomy, an ontology for human anatomy *

Friend of a Friend In sociology, a friend of a friend is a human contact that exists because of a mutual friend. Person C is a friend of a friend of person A when there is a person B that is a friend of both A and C. Thus the human relation "friend of a friend" is ...

, an ontology for describing persons, their activities and their relations to other people and objects *

Gene Ontology The Gene Ontology (GO) is a major bioinformatics initiative to unify the representation of gene and gene product attributes across all species. More specifically, the project aims to: 1) maintain and develop its controlled vocabulary of gene and g ...

for

genomics Genomics is an interdisciplinary field of biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, three-di ...

* Gellish English dictionary, an ontology that includes a dictionary and taxonomy that includes an upper ontology and a lower ontology that focusses on industrial and business applications in engineering, technology and procurement. * Geopolitical ontology, an ontology describing geopolitical information created by

Food and Agriculture Organization The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...

(FAO). The geopolitical ontology includes names in multiple languages (English, French, Spanish, Arabic, Chinese, Russian and Italian); maps standard coding systems (UN, ISO, FAOSTAT, AGROVOC, etc.); provides relations among territories (land borders, group membership, etc.); and tracks historical changes. In addition, FAO provides web services of geopolitical ontology and a module maker to download modules of the geopolitical ontology into different formats (RDF, XML, and EXCEL). See more information at FAO Country Profiles. * GAO (General Automotive Ontology) - an ontology for the automotive industry that includes 'car' extensions * GOLD, General Ontology for

Linguistic Description In the study of language, description or descriptive linguistics is the work of objectively analyzing and describing how language is actually used (or how it was used in the past) by a speech community. François & Ponsonnet (2013). All a ...

* GUM (Generalized Upper Model), a linguistically motivated ontology for mediating between clients systems and natural language technology * IDEAS Group, a formal ontology for enterprise architecture being developed by the Australian, Canadian, UK and U.S. Defence Depts. * Linkbase, a formal representation of the biomedical domain, founded upon Basic Formal Ontology. * LPL, Landmark Pattern Language * NCBO Bioportal, biological and biomedical ontologies and associated tools to search, browse and visualise * NIFSTD Ontologies from the

Neuroscience Information Framework The Neuroscience Information Framework is a repository of global neuroscience web resources, including experimental, clinical, and translational neuroscience databases, knowledge bases, atlases, and genetic/ genomic resources and provides many au ...

: a modular set of ontologies for the neuroscience domain. * OBO-Edit, an ontology browser for most of the Open Biological and Biomedical Ontologies * OBO Foundry, a suite of interoperable reference ontologies in biology and biomedicine * OMNIBUS Ontology, an ontology of learning, instruction, and instructional design * Ontology for Biomedical Investigations, an open-access, integrated ontology of biological and clinical investigations * ONSTR, Ontology for Newborn Screening Follow-up and Translational Research, Newborn Screening Follow-up Data Integration Collaborative, Emory University, Atlanta. * Plant Ontology for plant structures and growth/development stages, etc. * POPE, Purdue Ontology for Pharmaceutical Engineering * PRO, the Protein Ontology of the Protein Information Resource, Georgetown University * ProbOnto, knowledge base and ontology of

probability distribution In probability theory and statistics, a probability distribution is the mathematical function that gives the probabilities of occurrence of different possible outcomes for an experiment. It is a mathematical description of a random phenomeno ...

s. * Program abstraction taxonomy * Protein Ontology for

proteomics Proteomics is the large-scale study of proteins. Proteins are vital parts of living organisms, with many functions such as the formation of structural fibers of muscle tissue, enzymatic digestion of food, or synthesis and replication of DNA. In ...

* RXNO Ontology, for name reactions in chemistry *SCDO, the Sickle Cell Disease Ontology, facilitates data sharing and collaborations within the SDC community, amongst other applications (see list o
SCDO website
. * Sequence Ontology, for representing genomic feature types found on biological sequences * SNOMED CT (Systematized Nomenclature of Medicine—Clinical Terms) *

, a formal upper ontology * Systems Biology Ontology (SBO), for computational models in biology * SWEET, Semantic Web for Earth and Environmental Terminology * SSN/SOSA, The Semantic Sensor Network Ontology (SSN) and Sensor, Observation, Sample, and Actuator Ontology (SOSA) are W3C Recommendation and OGC Standards for describing sensors and their observations. * ThoughtTreasure ontology * TIME-ITEM, Topics for Indexing Medical Education * Uberon, representing

animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage ...

anatomical structures *

, a lightweight reference structure of 20,000 subject concept classes and their relationships derived from OpenCyc *

, a lexical reference system * YAMATO, Yet Another More Advanced Top-level Ontology The W3C Linking Open Data community project coordinates attempts to converge different ontologies into worldwide Semantic Web.

Libraries

The development of ontologies has led to the emergence of services providing lists or directories of ontologies called ontology libraries. The following are libraries of human-selected ontologies. * COLORE is an open repository of first-order ontologies in

Common Logic Common Logic (CL) is a framework for a family of logic languages, based on first-order logic, intended to facilitate the exchange and transmission of knowledge in computer-based systems. The CL definition permits and encourages the developmen ...

with formal links between ontologies in the repository. * DAML Ontology Library maintains a legacy of ontologies in DAML. * Ontology Design Patterns portal is a wiki repository of reusable components and practices for ontology design, and also maintains a list of ''exemplary ontologies''. * Protégé Ontology Library contains a set of OWL, Frame-based and other format ontologies. * SchemaWeb is a directory of RDF schemata expressed in RDFS, OWL and DAML+OIL. The following are both directories and search engines. * OBO Foundry is a suite of interoperable reference ontologies in biology and biomedicine. * Bioportal (ontology repository of NCBO) * OntoSelect Ontology Library offers similar services for RDF/S, DAML and OWL ontologies. * Ontaria is a "searchable and browsable directory of semantic web data" with a focus on RDF vocabularies with OWL ontologies. (NB Project "on hold" since 2004). * Swoogle is a directory and search engine for all RDF resources available on the Web, including ontologies. * Open Ontology Repository initiative * ROMULUS is a foundational ontology repository aimed at improving semantic interoperability. Currently there are three foundational ontologies in the repository: DOLCE, BFO and GFO.

Examples of applications

In general, ontologies can be used beneficially in several fields. * Enterprise applications. A more concrete example is SAPPHIRE (Health care) or ''Situational Awareness and Preparedness for Public Health Incidences and Reasoning Engines'' which is a

semantics Semantics (from grc, σημαντικός ''sēmantikós'', "significant") is the study of reference, meaning, or truth. The term can be used to refer to subfields of several distinct disciplines, including philosophy, linguistics and comp ...

-based health information system capable of tracking and evaluating situations and occurrences that may affect

public health Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the det ...

. *

Geographic information systems A geographic information system (GIS) is a type of database containing geographic data (that is, descriptions of phenomena for which location is relevant), combined with software tools for managing, analyzing, and visualizing those data. In a ...

bring together data from different sources and benefit therefore from ontological metadata which helps to connect the semantics of the data. * Domain-specific ontologies are extremely important in biomedical research, which requires named entity disambiguation of various biomedical terms and abbreviations that have the same string of characters but represent different biomedical concepts. For example, CSF can represent Colony Stimulating Factor or Cerebral Spinal Fluid, both of which are represented by the same term, CSF, in biomedical literature. This is why a large number of public ontologies are related to the life sciences. Life science data science tools that fail to implement these types of biomedical ontologies will not be able to accurately determine causal relationships between concepts.

References

External links

Knowledge Representation
at Open Directory Project
Library of ontologies

GoPubMed
using Ontologies for searching
ONTOLOG
(a.k.a.
Ontolog Forum
) - an Open, International, Virtual Community of Practice on Ontology, Ontological Engineering and Semantic Technology

Ontology Summit
- an annual series of events (first started in 2006) that involves the ontology community and communities related to each year's theme chosen for the summit.
Standardization of Ontologies
{{DEFAULTSORT:Ontology (Information Science) Knowledge engineering Technical communication Information science Semantic Web Knowledge representation Knowledge bases Ontology editors