[Nauty-list] geng for large sizes

Brendan McKay bdm at cs.anu.edu.au
Wed Sep 19 15:59:55 EST 2007

Thanks to Keith and Gordon for finding a problem in geng. Actually
it is fixed already in nauty version 2.4 even though I have no
recollection of fixing it.

The problem is that no graphs were produced for n > 28 when
none of -b,-t,-f,-m were given.

The simplest workaround is to add -m.  The best workaround is
to either patch geng.c and recompile, or to get version 2.4
from the web page.  I already applied the patch to version 2.2
as provided on the web page.

The required patch:  Change
    if (maxn + 4 > 8*sizeof(xword)) savemem = TRUE;
    if (maxn + 4 > 8*sizeof(xword)) savemem = sparse = TRUE;


Meanwhile, I put Beta 6 of version 2.4 on the web page.
It has no known bugs (so find some for me).  The latest set of
changes, from the tail of the file README is:

July 12, 2007:  Added -f option to directg.

Aug 14, 2007:  Added -i,-I,-K options to shortg, parallel to labelg.
              Since -k is used in labelg in place of -I, changed labelg
              to use -I also, with -k remaining as an undocumented
              compatibility feature.

Aug-Sep 2007: Minor things:
              * naututil-h.in now defines CPUTIME=0.0 as a last resort
              * gtools.c now implements EDGECODE (not used anywhere yet)
              * fixed definition of SG_FREE in nausparse.h (not used)
              * geng favours space over time for n > 28


Nauty page:  http://cs.anu.edu.au/~bdm/nauty/

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