struct::graph , in the struct module of Tcllib, provides commands to create and manipulate directed graphs.
- converts struct::graph structures to graphviz .dot format.
- Adds some algorithms to struct::graph.
- A specialized graph data structure used in expert system shells.
- official reference
dzach 2006-05-18: Is there an impementation for undirected graphs? Arcs may not be the best metaphor for concepts like air channels or coaxial Ethernet, although they can simulate one when paired.