[Nauty-list] malfunction of listg

William Rummler w.a.rummler at gmail.com
Mon Mar 14 16:05:28 EST 2011

> There is something curious going on with listg. I used it to bring
> several big files that geng had made into a human readable format. When
> I tried this on a 32 bit system (Solaris), the biggest input files all
> gave output files of identical size, some of them ending in the middle
> of a graph. When I tried it on a 64-bit system (Linux) to avoid this, I
> did get files of different sizes, but the sizes of the outfiles were in
> no way proportional to the sizes of the infiles. There was no error
> message. What is happening here and what can I do to get sensible output?

Unless you are using the "-a", "-A", or "-W" flags with listg, the
size of its output will depend on the density or sparseness of the
input graphs, since most of the output formats use adjacency lists
instead of adjacency matrices. If you have some files with very sparse
graphs and some files with very dense graphs, the former will have
smaller listg output-sizes than the latter.

Are there other indicators of insensible output on the 64-bit system,
i.e. strange-looking file contents? (Does the above resolve your

Regarding the 32-bit system, I can only guess that your files might be
too big for nauty to handle with a wordsize smaller than that of the
64-bit system.

- William

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