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D.6.16.5 discr
Procedure from library spcurve.lib (see spcurve_lib).
- Usage:
- discr(sem,n); sem ideal, n integer
- Assume:
- sem is the versal deformation of an ideal of codimension 2.
The first n variables of the ring are treated as variables
all the others as parameters.
- Return:
- ideal describing the discriminant
- Note:
- This is not a powerful algorithm!
Example:
| | LIB "spcurve.lib";
ring r=32003,(x(1),x(2),x(3)),ds;
ideal curve=x(1)*x(2),x(1)*x(3),x(2)*x(3);
matrix M=isCMcod2(curve);
list l=matrixT1(M,3);
def rneu=semiCMcod2(l[1],std(l[2]));
setring rneu;
discr(semi,3);
==> _[1]=A(1)*A(2)*A(3)
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