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D.2.4.20 intersectpar
Procedure from library grobcov.lib (see grobcov_lib).
- Usage:
- interectpar(list of ideals S)
list S=ideal I1,...,ideal Ik;
- Return:
- The intersection of the ideals I1 ... Ik in Q[x,a]
- Note:
- The routine is called in Q[a][x],
The ideals I1,..,Ik can be ideals depending only on [a] or on [x,a]
Example:
| | LIB "grobcov.lib";
"EAXMPLE:";
==> EAXMPLE:
if(defined(R)){kill R;}
ring R=(0,x,y,z),(x1,y1,z1),lp;
ideal I1=x+y*z*x1;
ideal I2=x-y*z*y1;
ideal I3=x+y+z*z1;
list S=I1,I2,I3;
S;
==> [1]:
==> _[1]=(y*z)*x1+(x)
==> [2]:
==> _[1]=(-y*z)*y1+(x)
==> [3]:
==> _[1]=(z)*z1+(x+y)
intersectpar(S);
==> _[1]=(y^2*z^3)*x1*y1*z1+(x*y^2*z^2+y^3*z^2)*x1*y1+(-x*y*z^2)*x1*z1+(-x^2*\
y*z-x*y^2*z)*x1+(x*y*z^2)*y1*z1+(x^2*y*z+x*y^2*z)*y1+(-x^2*z)*z1+(-x^3-x^\
2*y)
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