On Wednesday, January 20, 2016 at 1:04:49 PM UTC-8, John Cremona wrote:

>
> > Is there any reason to not make GF(16) behave as GF(16,'x') does,
> > unless specified otherwise? I do not see the point of requesting the
> > user to provide a character if (s)he does not care.
> >
>
> +1 for having a default, though I would choose 'a'.
>
>
There is a potential confusion there:

sage: ZX.<x>=ZZ[]
sage: ZY.<y>=ZZ[]
sage: F=GF(16,'x')
sage: R=F['x,u,v']
sage: S=F['y,u,v']
sage: S(x).degree()
0
sage: R(x).degree()
1
sage: S(y).degree()
1
sage: R(y).degree()
0

This is actually a bit of a mess: generator names are supposed to be used 
in figuring out coercion maps, but currently this doesn't seem to happen 
too much with GF(p^r) . [Really, F(y) should be an error, because it's 
totally not clear where y should go]. So currently, having a default name 
in GF doesn't seem to be too much of an issue because GF violates normal 
coercion rules. However, if this were fixed then a default generator name 
(especially when it's something usual such as x) would lead to odd 
interactions with coercions from various structures.

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