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 (includi ...

and

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 ...

, 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 sy ...

s used to construct

ontologies In computer science and information science, 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 ...

. They allow the encoding of

knowledge Knowledge can be defined as Descriptive knowledge, awareness of facts or as Procedural knowledge, practical skills, and may also refer to Knowledge by acquaintance, familiarity with objects or situations. Knowledge of facts, also called pro ...

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

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 quantifie ...

or on description logic.

Classification of ontology languages

Classification by syntax

Traditional syntax ontology languages

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 development o ...

- 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, Isla ...

(Developing Ontology-Grounded Methods and Applications) *

F-Logic F-logic ( frame logic) is a knowledge representation and ontology language. F-logic combines the advantages of conceptual modeling with object-oriented, frame-based languages and offers a declarative, compact and simple syntax, as well as the wel ...

(Frame Logic) * FO-dot (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) * OCML (Operational Conceptual Modelling Language) * OKBC ( Open Knowledge Base Connectivity) * PLIB (Parts LIBrary) * RACER

Markup ontology languages

These languages use a markup 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 (Ontology Inference Layer or Ontology Interchange Language) can be regarded as an ontology infrastructure for the Semantic Web. OIL is based on concepts developed in Description Logic (DL) and frame-based systems and is compatible with RDFS ...

(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 (RDF) * RDF Schema (RDFS) *

SHOE A shoe is an item of footwear intended to protect and comfort the 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 culture ...

Controlled natural languages

Attempto Controlled English Attempto Controlled English (ACE) is a controlled natural language, i.e. a subset of standard English with a restricted syntax and restricted semantics described by a small set of construction and interpretation rules. It has been under developmen ...

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 file ...

www.executable-english.com
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Classification by structure (logic type)

Frame-based

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

* OKBC * 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 Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers a ...

. 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. *

* CycL * FO-dot (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