|
3.12 minres
Syntax:
minres ( list_expression )
Type:
- list
Syntax:
minres ( resolution_expression )
Type:
- resolution
Purpose:
- minimizes a free resolution of an ideal or module
given by the list_expression, resp. resolution_expression.
Example:
| ring A=0,(x,y,z),Dp;
matrix d[3][3];
d[1,2]=-z;
d[1,3]=2x;
d[2,3]=-2y;
ncalgebra(1,d);
ideal i=x,y,z;
i=std(i);
resolution F=nres(i,0);
F;
==> 1 3 3 1
==> A <-- A <-- A <-- A
==>
==> 0 1 2 3
==> resolution not minimized yet
==>
int a;
for (a=1;a<=size(list(F));a++)
{
printf("Module: %s",a);
print(matrix(F[a]));
}
==> Module: 1
==> z,y,x
==> Module: 2
==> y, x, -1,
==> -z-2,0, x,
==> 0, -z+2,-y
==> Module: 3
==> x,
==> -y,
==> z
resolution MF=minres(F);
MF;
==> 1 3 3 1
==> A <-- A <-- A <-- A
==>
==> 0 1 2 3
==>
for (a=1;a<=size(list(MF));a++)
{
printf("Module: %s",a);
print(matrix(MF[a]));
}
==> Module: 1
==> y,x
==> Module: 2
==> -xy+2z+2,-x2,
==> y2, xy+z-2
==> Module: 3
==> x,
==> -y
|
See
mres;
nres.
|