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

artificial intelligence Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machine A machine is a physical system using Power (physics), power to apply Force, forces and control Motion, moveme ...

, ontology languages are

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 s ...

s used to construct ontologies. They allow the encoding of

knowledge Knowledge can be defined as awareness of facts or as practical skills, and may also refer to familiarity with objects or situations. Knowledge of facts, also called propositional knowledge, is often defined as true belief that is disti ...

about specific domains and often include reasoning rules that support the processing of that knowledge. Ontology languages are usually

declarative language In computer science, declarative programming is a programming paradigm—a style of building the structure and elements of computer programs—that expresses the logic of a computation without describing its control flow. Many languages that ap ...

s, are almost always generalizations of

frame language Frames are an artificial intelligence data structure used to divide knowledge into substructures by representing "stereotyped situations". They were proposed by Marvin Minsky in his 1974 article "A Framework for Representing Knowledge". Frames are ...

s, and are commonly based on either

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 quanti ...

or on description logic.

Classification of ontology languages

Classification by syntax

Traditional syntax ontology languages

* Common Logic - and its dialects * CycL *

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 ...

(Developing Ontology-Grounded Methods and Applications) * F-Logic (Frame Logic) *

FO-dot In computer science, FO(.) (a.k.a. FO-dot) is a knowledge representation language based on first-order logic (FO). It extends FO with types, aggregates (counting, summing, maximising ... over a set), arithmetic, inductive definitions, partial fu ...

(First-order logic extended with types, arithmetic, aggregates and inductive definitions) * KIF (Knowledge Interchange Format) ** Ontolingua based on KIF *

KL-ONE KL-ONE (pronounced "kay ell won") is a knowledge representation system in the tradition of semantic networks and frames; that is, it is a frame language. The system is an attempt to overcome semantic indistinctness in semantic network represen ...

* KM programming language *

LOOM (ontology) Loom is a knowledge representation language developed by researchers in the artificial intelligence research group at the University of Southern California's Information Sciences Institute. The leader of the Loom project and primary architect ...

* OCML (Operational Conceptual Modelling Language) *

OKBC Open Knowledge Base Connectivity (OKBC) is a protocol and an API for accessing knowledge in knowledge representation systems such as ontology repositories and object–relational databases. It is somewhat complementary to the Knowledge Interchang ...

(

Open Knowledge Base Connectivity Open Knowledge Base Connectivity (OKBC) is a protocol and an API for accessing knowledge in knowledge representation systems such as ontology repositories and object–relational databases. It is somewhat complementary to the Knowledge Intercha ...

) * PLIB (Parts LIBrary) * RACER

Markup ontology languages

These languages use a

markup Markup or mark-up can refer to: * Markup language, a standardized set of notations used to annotate a plain-text document's content to give information regarding the structure of the text or instructions for how it is to be displayed ** Lightweigh ...

scheme to encode knowledge, most commonly with

XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. ...

. * DAML+OIL * Ontology Inference Layer (OIL) *

Web Ontology Language The Web Ontology Language (OWL) is a family of knowledge representation languages for authoring ontologies. Ontologies are a formal way to describe taxonomies and classification networks, essentially defining the structure of knowledge for vario ...

(OWL) *

Resource Description Framework The Resource Description Framework (RDF) is a World Wide Web Consortium (W3C) standard originally designed as a data model for metadata. It has come to be used as a general method for description and exchange of graph data. RDF provides a variety of ...

(RDF) * RDF Schema (RDFS) *

SHOE A shoe is an item of footwear intended to protect and comfort the Foot, human foot. They are often worn with a sock. Shoes are also used as an item of decoration and fashion. The design of shoes has varied enormously through time and from cult ...

Controlled natural languages

* Attempto Controlled English

Open vocabulary natural languages

Executable English In computing, executable code, an executable file, or an executable program, sometimes simply referred to as an executable or binary, causes a computer "to perform indicated tasks according to encoded instructions", as opposed to a data fil ...

www.executable-english.com
/ref>

Classification by structure (logic type)

Frame-based

Three languages are completely or partially frame-based languages. * F-Logic *

* KM

Description logic-based

Description logic provides an extension of

s, without going so far as to take the leap to

and support for arbitrary predicates. *

* RACER * OWL. Gellish is an example of a combined ontology language and ontology that is description logic based. It distinguishes between the semantic differences among others of: * relation types for relations between concepts (classes) * relation types for relations between individuals * relation types for relations between individuals and classes It also contains constructs to express queries and communicative intent.

First-order logic-based

Several ontology languages support expressions in

and allow general predicates. * Common Logic * CycL *

(First-order logic extended with types, arithmetic, aggregates and inductive definitions) * KIF

Notes

References

* Oscar Corcho, Asuncion Gomez-Perez,
A Roadmap to Ontology Specification Languages
' (2000)
''Introduction to Description Logics'' – DL course
by Enrico Franconi, Faculty of Computer Science, Free University of Bolzano, Italy {{Non-classical logic Modeling languages