Hi, the sender is Jamel Dammak his email adress is jdam...@yahoo.fr
Le dimanche 11 décembre 2016 22:08:50 UTC+1, Harald Schilly a écrit :
>
> This came in via the trac account request. I don't know the sender's
> email address ...
>
> -- h
>
>
> ---------- Forwarded message ----------
> From: 'Jamel Dammak' via sage-trac-account <sage-tra...@googlegroups.com
> <javascript:>>
> Date: Sun, Dec 11, 2016 at 10:01 PM
> Subject: [sage-trac-account] Corrections about the function "is_prime"
> for graphs
> To: "sage-tra...@googlegroups.com <javascript:>" <
> sage-tra...@googlegroups.com <javascript:>>
>
>
> Dear sir,
>
> there is an error concerning the function "is_prime" for graphs in
> Sagemath, section Graph Theory.
>
> Here is a conter-example.
>
> g1=Graph({0:[1,4],1:[0,2,4],2:[1,3,4],3:[2],4:[0,1,2]});g2=Graph({0:[1],1:[0,2,4],2:[1,3,4],3:[2,4],4:[1,2,3]})
>
>
> #g1.show();g2.show();
> #[1,4] is a module of g1 so g1 is not prime
> g2.is_isomorphic(g1), g1.is_prime(),g2.is_prime()
>
> This is a conter-example with two isomorphic graphs g1 and g2 on 5
> vertices giving two different results
> with the function "is prime".
>
> I have an algorithm giving the list of all prime graphs on at most 8
> vertices.
>
> Best regards.
>
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