The package in question is downgraded to an experimental one.
A robust and efficient replacement, implementing modular decomposition
of graphs (and digraphs), for the corresponding functionality would be
great.
Perhaps this should be made a GSoC project?
On Tuesday, January 31, 2017 at 3:54:12 PM UTC, kcrisman wrote:
>
>
>
> On Monday, January 30, 2017 at 9:48:22 AM UTC-5, Thierry
> (sage-googlesucks@xxx) wrote:
>>
>> Hi,
>>
>> On Mon, Jan 30, 2017 at 03:44:06AM -0800, jamel Dammak wrote:
>> > 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=G
>> > raph({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
>> > #[2,4] is a module of g2 so g2 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.
>>
>>
>> Great, go ahead, ask for a trac account, and propose your changes.
>>
>
> I've reported this at https://trac.sagemath.org/ticket/22281
> Note it depends on an optional package, so this may be part of the issue.
>
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