>
> It is definitely a bug in the dimension method.
>
could you open a ticket and post the link here?
Am Sonntag, 3. Mai 2015 15:25:13 UTC+2 schrieb mmarco:
>
> It is definitely a bug in the dimension method.
>
> If singular can handle the ring, sage asks singular to compute the
> dimension, which does correctly (the -1 is the singular convention for
> empty varieties).
>
> The problem is that when the field is not supported by singular (which
> happens with QQbar or finite fields of characteristic bigger than 2^31) ,
> then sage falls back to its own toy implementation. In that case, it
> appears that the empty case is not treated separatedly than the zero
> dimensional case.
>
>
>
> El viernes, 1 de mayo de 2015, 21:18:55 (UTC+2), gjorgen...@my.fit.edu
> escribió:
>>
>> Hi,
>>
>> For the following ideal, dimension() returns 0,
>> {{{
>> R.<s0,s1>=QQbar[]
>> I=R.ideal([ s0 + 1, s0*s1 + s0 + s1 + 1, (-2)*s0 + 1, (-10)*s1 + 5,
>> 5*s0^2 + 10*s0*s1 ])
>> I.dimension()
>> }}}
>> but its variety is empty.
>>
>> Also for any other ring, dimension() returns -1 for this ideal. Is this a
>> bug with dimension()? The documentation for dimension() doesn't seem to
>> mention the -1 case.
>> It provides the following example,
>> {{{
>> R.<x,y> = PolynomialRing(GF(2147483659),order='lex')
>> I = R.ideal([x*y,x*y+1])
>> I.dimension()
>> }}}
>> which yields dimension 0 for the ideal, yet the corresponding variety is
>> empty.
>>
>> What is the expected behavior for dimension()? When the variety of the
>> ideal in question has no points is dimension() always supposed to return -1?
>>
>
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