Common Logic (CL) is a framework for a family of logic languages, based on

first-order logic First-order logic, also called predicate logic, predicate calculus, or quantificational logic, is a collection of formal systems used in mathematics, philosophy, linguistics, and computer science. First-order logic uses quantified variables over ...

, intended to facilitate the exchange and transmission of

knowledge Knowledge is an Declarative knowledge, awareness of facts, a Knowledge by acquaintance, familiarity with individuals and situations, or a Procedural knowledge, practical skill. Knowledge of facts, also called propositional knowledge, is oft ...

computer A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...

-based systems. The CL definition permits and encourages the development of a variety of different syntactic forms, called ''dialects''. A dialect may use any desired syntax, but it must be possible to demonstrate precisely how the concrete syntax of a dialect conforms to the abstract CL semantics, which are based on a model theoretic interpretation. Each dialect may be then treated as a

formal language In logic, mathematics, computer science, and linguistics, a formal language is a set of strings whose symbols are taken from a set called "alphabet". The alphabet of a formal language consists of symbols that concatenate into strings (also c ...

. Once syntactic conformance is established, a dialect gets the CL semantics for free, as they are specified relative to the abstract syntax only, and hence are inherited by any conformant dialect. In addition, all CL dialects are comparable (i.e., can be automatically translated to a common language), although some may be more expressive than others. In general, a less expressive subset of CL may be translated to a more expressive version of CL, but the reverse translation is only defined on a subset of the larger language.

The ISO Standard

Common Logic is published by

ISO The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. Me ...

as "ISO/IEC 24707:2007 - Information technology — Common Logic (CL): a framework for a family of logic-based languages". It is available for purchase from ISO's catalog, and is freely available from ISO's index of publicly available standards.Common Logic Standard Second Edition
/ref> The CL Standard includes specifications for three dialects, the Common Logic Interchange Format (CLIF) (Annex A), the Conceptual Graph Interchange Format (CGIF) (Annex B), and an

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

-based notation for Common Logic (XCL) (Annex C). The semantics of these dialects are defined in the Standard by their translation to the abstract syntax and semantics of Common Logic. Many other logic-based languages could also be defined as subsets of CL by means of similar translations; among them are the RDF and

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 ...

languages, which have been defined by the

W3C The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web. Founded in 1994 by Tim Berners-Lee, the consortium is made up of member organizations that maintain full-time staff working together in ...

. The ISO standard's development began in June 2003 under Working Group 2 (Metadata) of Sub-Committee 32 (Data Interchange) under

ISO/IEC JTC 1 ISO/IEC JTC 1, entitled "Information technology", is a joint technical committee (JTC) of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). Its purpose is to develop, maintain an ...

, and was completed in October 2007. A technical corrigendum, correcting some errors in the original standard, is being prepared at the time being.

Implementations

COLORE
is a repository of Common Logic Ontologies
Hets
supports Common Logic
cltools
is a PROLOG library with partial support for Common Logic

The ISO Standard

Implementations

See also

References

Further reading