[Nauty] What are the differences between using and not using the -t option in labelg for canonical graph labeling?

[Brendan McKay]

labelg always makes a canonical labelling, but what "canonical" means 
depends on the options.
    -t, -S, -f, -i, -I, -K all change the meaning.

In order to compare some family of graphs, you have to use the same 
options for all of them.

Brendan.


On 21/7/2024 11:30 pm, lczhangmath via Nauty wrote:
> Hello, everyone,
>
>
> I noticed the option -t in labelg. I would like to ask, if I don't use the -t option, will the obtained labels still be canonical? In other words, if I want to get the canonical labeling of a graph, do I have to use the -t option? I noticed that when I don't use the -t option for canonical graph labeling, the graph's labels also change. So, what is labelg doing at this time? Do the obtained labels have some special meaning?
>
>
>   echo 'E{EG' |showg
>
>
>
>
> Graph 1, order 6.
>    0 : 1 2 3 5;
>    1 : 0 2;
>    2 : 0 1;
>    3 : 0 4;
>    4 : 3 5;
>    5 : 0 4;
>
>
>
>
> echo 'E{EG' |labelg |showg
>
>
> Graph 1, order 6.
>    0 : 4 5;
>    1 : 4 5;
>    2 : 3 5;
>    3 : 2 5;
>    4 : 0 1;
>    5 : 0 1 2 3;
>
>
>
>
> Use  labelg  -t:
> echo 'E{EG' |labelg  -t|showg
>
>
> Graph 1, order 6.
>    0 : 3 4;
>    1 : 2 5;
>    2 : 1 5;
>    3 : 0 5;
>    4 : 0 5;
>    5 : 1 2 3 4;
>
>
> Best wishes,
> Licheng
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