[Nauty-list] malfunction of listg

Brendan McKay bdm at cs.anu.edu.au
Mon Mar 14 16:45:05 EST 2011

Please clarify: is this the catg problem mentioned in other mail
or a separate problem?

What was the size of the truncated output files? If it was
approximately 2.1 GB, you have probably met the limit of 32-bit i/o

Depending on your operating system, you might be able to bypass the
problem by piping the output through "cat".
Instead of
    listg file >outputfile
    listg file | cat >outputfile

The next version of nauty uses 64-bit i/o functions where available,
so this problem will disappear if your operating system is not too
old and you aren't using a disk formatted in a way that limits file
sizes (like some "FAT" formats).


* William Rummler <w.a.rummler at gmail.com> [110314 16:05]:
> > 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
> concern?)
> 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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