On Thu, 13 Dec 2018 at 17:22, John Cremona <john.crem...@gmail.com> wrote:

>
>
> On Thu, 13 Dec 2018 at 16:42, Vincent Delecroix <20100.delecr...@gmail.com>
> wrote:
>
>> Le 13/12/2018 à 17:17, Jeroen Demeyer a écrit :
>> > On 2018-12-13 13:11, John Cremona wrote:
>> >> The problem is that t is a pari gen and Sage tries too hard to compare
>> >> that with python 0.
>> >
>> > This has nothing to do with Sage or Python, the "problem" is that PARI
>> > considers [0] and 0 equal.
>>
>> Which make sense if you think of [0] as a polynomial of degree 0, and
>> more generally as the zero vector. Sage does the same to some extent
>>
>> sage: 0 == vector([0])
>> True
>> sage: 0 == QQ['x'].zero()
>> True
>>
>> > Personally, I think that Sage (really the package cypari2 which
>> > implements the PARI <-> Python interface) should follow the PARI
>> > semantics, even if they are dubious.
>>
>> +1
>>
>
> Well that makes fixing this easier since all we need to do is change one
> line in the is_isomorphic() method.  I assume that you agree that there is
> a top-level bug at least!
>

Some apologies seem to be required since I found the same bug 3 months ago
and made a ticket https://trac.sagemath.org/ticket/26239 with exactly the
same diagnosis.  I had forgotten.  Well, at least I don't have to make a
new ticket, just fix it.


>
> John
>
>
>>
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