GML-Format for SNDlib

In SNDlib, all problems and solutions are available for download in GML (Graph Modelling Language) format, a portable standardised format for graphs. For viewing, editing and analysing graphs written in GML we recommend the free Graph Editor yEd.

The format of a problem-GML is quite simple. There are nodes and links. DIRECTED/BIDIRECTED links have source/target arrows, UNDIRECTED links do not.

The following rules apply to a solution-GML:

• The thickness of a link corresponds to the installed capacity.
• A link which is not contained in the solution topology is illustrated as a grey-dashed line.
• The color of a link corresponds to its maximum usage (maximum flow / capacity) in any operating state. The darker the color, the higher the usage of the link. A black link indicates full use of the capacity. A light red link is nearly not used in all operating states.

You can create a GML file out of an SNDlib instance either with the provided Java classes (see our download page) or by using the small C program createGML.c kindly provided by Paula Carroll.