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## Re: [igraph] Creating all possible non-isomorphic graphs from N nodes

**From**: |
Tamás Nepusz |

**Subject**: |
Re: [igraph] Creating all possible non-isomorphic graphs from N nodes |

**Date**: |
Sun, 28 Jul 2013 20:05:40 +0200 |

>* 1. If I have N nodes, what is the shortest way to create all possible *
>* non-isomorphic graphs? E.G for N=2 nodes, there are 2 possible graphs, N=3, *
>* there are 4, N=4 there are 11, N=5 there are 34, etc*
The shortest way is to download them from Brendan McKay's page ;) He has
generated all the nonisomorphic connected graphs up to 10 vertices with his
'nauty' software (more precisely its "geng" program):
http://cs.anu.edu.au/~bdm/data/graphs.html
By the way, the OEIS sequence A000088 gives you the number of all the connected
nonisomoprhic graphs as a function of n:
http://oeis.org/A000088
According to this, it seems quite unpractical to generate all these graphs even
for n=11.
>* 2. Is it possible to have an array of graph objects of the form *
>* G[1],G[2]...G[10]...?*
Yes, it is. You did not mention which language you use igraph from so it's hard
to be any more specific than this.
Cheers,
--
T.