[Nauty-list] generating some graphs

Brendan McKay bdm at cs.anu.edu.au
Fri Sep 7 09:05:15 EST 2007


I think it is just being slow, but I'll check.  The difference between
the two computers is probably just different i/o buffer size.

In any case, for bipartite graphs with known partition it is much
faster to use genbg:

  % genbg -cu -d3:4 -D3:4 12 9
  >A genbg n=12+9 e=36:36 d=3:4 D=3:4 c
  >Z 22651 graphs generated in 11.21 sec


* zstanic at matf.bg.ac.yu <zstanic at matf.bg.ac.yu> [070907 03:54]:
> I am trying to generate some connected (3,4)-semiregular bipartite graphs
> on 21 vertices and 36 edges. In this purpose I run the following command:
> geng 21 -c -b 36:36 -d3 -D4 > out.txt
> And everything is going fine until the moment when the program stops
> writing the graphs into the output file but still running. In the first
> two situations the program brokes in the same place. In that moment
> out.txt had 848kb, and the last 5 lines of this file are:
> T?????????W?k?[?@w?Po at k?Dg?SgF_??@J?
> T?????????W?k?[?@w?Po at k?Dg?QgF_??AJ?
> T?????????W?k?[?@w?Po at k?Dg?EgF_??GJ?
> T?????????W?k?Y??{?M_ at k?@sE_O at oOBGG?
> T?????????W?k?
> In the third situation (on a different computer), the program brokes in a
> different place. In that moment out.txt had 832kb, and the last 5 lines of
> this file are:
> T???????????{?b_?N?BgQQ?sC at d?AWGAAW?
> T???????????{?b_?N?BgQQ?sCCT?AK_?oK?
> T???????????{?b_?N?BgQQ?sCAT?Dc??C[?
> T???????????{?b_?N?BgQQ?sCAT?@k?A?[?
> T???????
> In both casses, one graph is not completed. And in both cases I waited a
> few hours to see if something changes, but the output was the same all
> this time.
> Note: I am using nauty 2.2.
> Can somebody explain this?
> Zoran Stanic,
> University of Belgrade, Serbia
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