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D.2.4.25 DifConsLCSets
Procedure from library grobcov.lib (see grobcov_lib).
- Return:
- A list of locally closed sets equivalent to the difference S= A "" B.
Lc=[ [1][p1,q1]] [[2][p2,q2]]..],
For obtaining the canonical representation into levels of
the constructible A "" B one have to apply ConsLevels and
then optatively Levels.
Example:
| | LIB "grobcov.lib";
// EXAMPLE:
if(defined(R)){kill R;}
ring R=(0,x,y,z,t),(x1,y1),lp;
ideal a1=x;
ideal a2=x,y;
ideal a3=x,y,z;
ideal a4=x,y,z,t;
ideal b1=y;
ideal b2=y,z;
ideal b3=y,z,t;
ideal b4=1;
list L1=a1,a2,a3,a4;
list L2=b1,b2,b3,b4;
L1;
==> [1]:
==> _[1]=(x)
==> [2]:
==> _[1]=(x)
==> _[2]=(y)
==> [3]:
==> _[1]=(x)
==> _[2]=(y)
==> _[3]=(z)
==> [4]:
==> _[1]=(x)
==> _[2]=(y)
==> _[3]=(z)
==> _[4]=(t)
L2;
==> [1]:
==> _[1]=(y)
==> [2]:
==> _[1]=(y)
==> _[2]=(z)
==> [3]:
==> _[1]=(y)
==> _[2]=(z)
==> _[3]=(t)
==> [4]:
==> _[1]=1
def LL=DifConsLCSets(L1,L2);
LL;
==> [1]:
==> [1]:
==> _[1]=(x)
==> [2]:
==> _[1]=(y)
==> _[2]=(x)
==> [2]:
==> [1]:
==> _[1]=(z)
==> _[2]=(y)
==> _[3]=(x)
==> [2]:
==> _[1]=(t)
==> _[2]=(z)
==> _[3]=(y)
==> _[4]=(x)
def LLL=ConsLevels(LL);
LLL;
==> [1]:
==> _[1]=(x)
==> [2]:
==> _[1]=(y)
==> _[2]=(x)
==> [3]:
==> _[1]=(z)
==> _[2]=(y)
==> _[3]=(x)
==> [4]:
==> _[1]=(t)
==> _[2]=(z)
==> _[3]=(y)
==> _[4]=(x)
==> [5]:
==> _[1]=1
def LLLL=Levels(LLL);
LLLL;
==> [1]:
==> [1]:
==> 1
==> [2]:
==> [1]:
==> _[1]=(x)
==> [2]:
==> _[1]=(y)
==> _[2]=(x)
==> [2]:
==> [1]:
==> 3
==> [2]:
==> [1]:
==> _[1]=(z)
==> _[2]=(y)
==> _[3]=(x)
==> [2]:
==> _[1]=(t)
==> _[2]=(z)
==> _[3]=(y)
==> _[4]=(x)
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