[Nauty] generate signed graphs

[Brendan McKay]

No, because the notion of isomorphism does not correspond.
An isomorphism between signed graphs is allowed to reverse edges.

Brendan.

On 16/12/2023 5:11 pm, guenter stertenbrink via Nauty wrote:
> signed graph = directed graph ?!
> maybe without double-direction-edges
>
>
> Am 15.12.2023 04:00 schrieb lczhangmath via Nauty:
>> A signed graph is a graph in which each edge has a plus or minus sign.
>> Two signed graphs are isomorphic if their underlying graphs are
>> isomorphic through a mapping under which signs of edges are preserved.
>>
>>
>> Given an underlying graph G, to obtain all non-isomorphic directed
>> graphs, I know that nauty has the directg function. Similarly, for
>> signed graphs, is it possible to design a similar function to obtain
>> all non-isomorphic signed graphs with G as the underlying graph?
>>
>>
>> PS: I haven't found tools for generating (connected) signed graphs
>> with n vertices either. So I posted a corresponding question on
>> MathOverflow; see
>> https://mathoverflow.net/questions/460413/generate-all-non-isomorphic-signed-graphs 
>>
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