ConceptualGraphs

http://www.jfsowa.com/cg/

TimBernersLee compares with the SemanticWeb : http://www.w3.org/DesignIssues/CG.html

CMAP Tools : http://cmap.ihmc.us/

See also :

• TopicMaps

• RDF

• GraphML

• OnNetworks

• CategoryTheory