A World of Conceptual Graphs

Conceptual graphs (CGs) are a system of logic based on the existential graphs of Charles Sanders Peirce and the semantic networks of artificial intelligence. They express meaning in a form that is logically precise, humanly readable, and computationally tractable. With their direct mapping to language, conceptual graphs serve as an intermediate language for translating computer-oriented formalisms to and from natural languages. With their graphic representation, they serve as a readable, but formal design and specification language. CGs have been implemented in a variety of projects for information retrieval, database design, expert systems, and natural language processing.

Introductions to Conceptual Graphs

  • John F. Sowa, Information Processing in Mind and Machine, Reading, MA: Addison-Wesley, 1984.

  • Simon Polovina and John Heaton, "An Introduction to Conceptual Graphs," AI Expert, pp. 36-43, 1992.

  • John F. Sowa, "Conceptual Graphs Summary," in Conceptual Structures: Current Research and Practice, P. Eklund, T. Nagle, J. Nagle, and L. Gerholz (Eds.), Ellis Horwood, pp. 3-52, 1992.

  • Simon Polovina, "An Introduction to Conceptual Graphs" in Conceptual Structures: Knowledge Architectures for Smart Applications, U. Priss, S. Polovina, R. Hill (Eds.), Lecture Notes in Artificial Intelligence (LNAI 4604), Springer, pp. 1-15, 2007.

  • John F. Sowa, Knowledge Representation : Logical, Philosophical, and Computational Foundations, is not limited to conceptual graphs, but provides broad coverage of the entire field. It is available from Barnes and Noble books and Amazon.com.

  • Aalborg University's Department of Communication has developed an excellent Online Conceptual Graphs course.

Conceptual Graphs Standard Notation

Current Standard

There is a standard for the Conceptual Graphs Interchange Format (CGIF). This standard was developed in conjunction with the ISO Common Logic Project, which seeks to standardize a form of logic for knowledge interchange, and includes three syntaxes for Common Logic, one of which is CGIF in Annex B. Comments and suggestions on the entire standard are welcome; see the web site for more details.

Earlier Proposals

Here are some documents that may be of some historical interest. Note that CGIF has undergone significant changes from these documents; see the current standard (above).

A very old draft proposed (c. 1998) for conceptual graphs:

Conceptual Graph Bibliographies

John F. Sowa's bibliography page

ICCS Conferences dblp:Computer Science bibliography page

Research Groups and Projects

Aalborg University - Department of Communication
Online Conceptual Graphs course

INSEA, Morocco
Amine Group deals in knowledge base and expert systems, natural language processing, Case Based Reasoning and learning, Intelligent Tutoring Systems and Multi-Agent Systems

Sheffield Hallam University, UK
CSRG (Conceptual Structures Research Group)

Universite Laval, Quebec City, Canada
Cognitive Informatics Laboratory

University of Montpellier 2, CNRS and INRA


Amine - a multi-layer platform dedicated to the development of Intelligent Systems and Multi-agent Systems.

CharGer - a prototype conceptual graph editor developed at the University of Alabama in Huntsville, free for noncommercial use, and runs under Java.

CG Mars Lander - fast conceptual graph retrieval and question answering tool, available for joint development and industrial funding.

CoGITaNT - several useful utilities: a set of library routines in C++ for conceptual modeling, some knowledge bases in conceptual graphs, and an XML specification for CGXML.

CPE - a modular environment that provides modules to give functionality to a user without having to take the whole environment. Currently, there is a CGIF editor, ARCEdit and other CG Operations (Projection and Maximal Join) should be available in the future.

GoGui - a free graph-based visual tool, developed in Java, for building Conceptual Graph knowledge bases represented in COGXML format, compatible with CoGITaNT (see above).

Prolog+CG - an object-oriented extension of PROLOG, based on CG. CG (both simple and compound) is a basic data structure, like term. PROLOG+CG is implemented with Java.

WebKB - tools for information retrieval and knowledge representation.

At ICCS'05 in Kassel, Germany, a discussion was held about how to further the progress of CG tools. Here is a summary of the discussion.

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We are not updating this website at present but remains available for historical interest.
At https://iccs-conference.org/ you can find what is currently happening with Conceptual Graphs. Thanks for visiting!