Group theory convention for composition is the same as in GAP and Magma. It
would be crazy to change it for a variety of reasons...
Whereas Permutation comes from combinatorics, I don't know why they took a
different default.
On Mon, 15 Jun 2020, 16:42 'Paul Mercat' via sage-devel, <
sage-devel@googlegroups.com> wrote:
> Thank you for your answers.
>
> It's very confusing to write a right action to the left : we write g(i)
> and not (i)g.
> By default it should be a left action.
>
> And its very confusing that PermutationGroup and Permutation doesn't give
> the same matrix for the same permutation.
> I think that Sage should be coherent with itself as much as possible, and
> that it should choose the most natural convention.
>
> Best regards,
> Paul
>
> Le lundi 15 juin 2020 17:30:33 UTC+2, David Joyner a écrit :
>>
>>
>>
>> On Mon, Jun 15, 2020 at 11:21 AM 'Paul Mercat' via sage-devel <
>> sage-...@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.
>>>>
>>> --
>>> You received this message because you are subscribed to the Google
>>> Groups "sage-devel" group.
>>> To unsubscribe from this group and stop receiving emails from it, send
>>> an email to sage-...@googlegroups.com.
>>> To view this discussion on the web visit
>>> https://groups.google.com/d/msgid/sage-devel/e4095a01-08f8-4aa1-924d-2c4494aeddd3o%40googlegroups.com
>>> <https://groups.google.com/d/msgid/sage-devel/e4095a01-08f8-4aa1-924d-2c4494aeddd3o%40googlegroups.com?utm_medium=email&utm_source=footer>
>>> .
>>>
>> --
> You received this message because you are subscribed to the Google Groups
> "sage-devel" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to sage-devel+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/sage-devel/fa42b74e-c614-426e-96c3-bd7fe48ad4d4o%40googlegroups.com
> <https://groups.google.com/d/msgid/sage-devel/fa42b74e-c614-426e-96c3-bd7fe48ad4d4o%40googlegroups.com?utm_medium=email&utm_source=footer>
> .
>
--
You received this message because you are subscribed to the Google Groups
"sage-devel" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-devel+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/sage-devel/CAAWYfq0p_3mcA0zJn%3DTLkrWDy7sx49Nex2%2BA%3Dvrrue1zf3wdvQ%40mail.gmail.com.
