On Mon, Jun 15, 2020 at 11:21 AM 'Paul Mercat' via sage-devel <
sage-devel@googlegroups.com> wrote:
> Another bug with PermutationGroup:
>
> {{
> g1,g2 = PermutationGroup([(1,2,3,4), (1,3,2,4)]).gens()
> (g1*g2)(3), g1(g2(3))
> }}
>
> should gives two times the same result, but it is not the case...
> The action of the group on {1,2,3,4} is not an action !
>
Did you mean to say the action on {1,2,3,4} is not a left action?
Some prefer right actions....
>
> Le lundi 15 juin 2020 16:58:18 UTC+2, Paul Mercat a écrit :
>>
>> Hi !
>>
>> Sage doesn't compute correctly the matrix of a Permutation:
>>
>> matrix(Permutation('(1,2,3,4)'))
>>
>> return a wrong answer: it returns the inverse of the correct result.
>> The product of matrices of permutations must be equal to the matrix of
>> the composition.
>>
>> If we do:
>>
>> PermutationGroup([(1,2,3,4)]).gens()[0].matrix()
>>
>> then we get the correct result.
>>
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