However not enforcing distinct variable names breaks the following method:
sage: R.<x,x> = QQ[]
sage: R.gens_dict()
{'x': x}
(which is what I'd use to implement algebra_generators). So one must be
somewhat careful.
Best,
Travis
On Monday, September 29, 2014 7:44:35 AM UTC-7, Volker Braun wrote:
>
> We talked about this once, afair it is the same in Magma. Really, there is
> no reason for forbidding it. And deep inside your own code you might want
> to add a variable to a polynomial ring given to you by the user, and it
> would be inconvenient to have to pick a letter that is not yet present in
> the user input.
>
>
>
> On Monday, September 29, 2014 3:38:34 PM UTC+1, Joao Alberto de Faria
> wrote:
>>
>> While reviewing some code, I realized that the following is currently
>> allowed:
>> P.<x,x,x,x,x,x> = PolynomialRing(QQ,6)
>> P
>>
>> Multivariate Polynomial Ring in x, x, x, x, x, x over Rational Field
>>
>> I believe that an object should not be allowed to have repeat instances of
>> the same variable names. I don't get any actual wrong answers, but I feel as
>> if it
>> should be addressed.
>>
>> After looking around, I have found two separate instances in the code base
>> for _assign_names, in category_object.pyx and parent_gens.pyx, both in
>> sage/structure. I think that the code should check for duplicates at this
>> point. However this seems too high up in the sage hierarchy for me to want
>> to
>> mess around with it in good conscious.
>>
>> Is there any reason the code currently operates as is? Or do people agree
>> that this needs to be fixed?
>>
>>
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