Editing Conceptual graph (section)

=== Graph-based knowledge representation and reasoning model ===
Key features of GBKR, the graph-based knowledge representation and reasoning model developed by Chein and Mugnier and the Montpellier group, can be summarized as follows:{{sfn|Chein|Mugnier|2009}}

* All kinds of knowledge (ontology, rules, constraints and facts) are labeled graphs, which provide an intuitive and easily understandable means to represent knowledge.
* Reasoning mechanisms are based on graph notions, basically the classical notion of [[graph homomorphism]]; this allows, in particular, to link basic reasoning problems to other fundamental problems in computer science (e.g., problems concerning [[Conjunctive query|conjunctive queries]] in [[relational database]]s, or [[constraint satisfaction problem|constraint satisfaction problems]]).
* The formalism is logically founded, i.e., it has a semantics in [[first-order logic]] and the inference mechanisms are sound and complete with respect to deduction in first-order logic.
* From a computational viewpoint, the graph homomorphism notion was recognized in the 1990s as a central notion, and complexity results and efficient algorithms have been obtained in several domains.

COGITANT and COGUI are tools that implement the GBKR model. COGITANT is a library of [[C++]] classes that implement most of the GBKR notions and reasoning mechanisms. COGUI is a graphical user interface dedicated to the construction of a GBKR knowledge base (it integrates COGITANT and, among numerous functionalities, it contains a translator from GBKR to [[RDF Schema|RDF/S]] and conversely).