For sparse graphs, there is a related format called sparse6 which can be mixed with graph6 at will - the reader will figure out which format it is being asked to read. The sparse format is vital for storing things like large cubic graphs in a moderate amount of space. However, for those without the time or inclination to install the full nauty package, there is a standalone graph reader, which is suitable for both graph6 and the new sparse6 format. Please let either of us know if you have any problems compiling it, giving as much information about the computer, operating system and compiler as possible. Write graphs in human-readable format.
Defaults are standard input and standard output.
The first graph is number 1. A second number which is empty or zero means infinity. Here are some sample ways in which you can view the graphs, or prepare them for further computer processing in your preferred format. The program readg was written by Brendan McKay.