Read-only forum archive

ideal multiplicity

ideal multiplicity

Bruna · Wed May 25, 2011 11:55 am

Please, I'd like to know if I can compute with Singular the Samuel multiplicity of an ideal (which is a system of paramaters but not necessarily a maximal ideal) in a quocient ring.

Thanks,

Bruna

Re: ideal multiplicity

gorzel · Wed May 25, 2011 2:06 pm

See mult http://www.singular.uni-kl.de/Manual/la ... htm#SEC315
Quote:
If the input is a standard basis of an ideal in a (local) ring with respect to a local degree ordering then it returns the multiplicity of the ideal (in the sense of Samuel, with respect to the maximal ideal).

Re: ideal multiplicity

Bruna · Thu May 26, 2011 12:05 pm

Hello,

if for instance, I put I=x2+y3 in the ring O_2 and mult(I), I will calculate the multiplicity of the maximal ideal in O_2/I, is that right?

But, what I wanna do is calculate the multiplicity of a third ideal, for example J=x, in the quocient ring O_2/I. Is that possible?

Bruna

Re: ideal multiplicity

hannes · Mon Jun 27, 2011 1:27 pm

yes, that is possible, set the correct basering:
Code:
ring r=....;
ideal I=....;
qring q=std(I);
ideal J=....;
mult(std(J));