Bug #279
Bug in Radical (actually a RingHom problem)
Description
this gives an error:
/**/ M:=6; Use R::=QQ[x[1..M,1..M]], DegLex; /**/ J := ***Ideal( x[2,4]x[3,6] - x[2,6]x[3,4], x[1,3]x[2,4] - x[1,4]x[2,3], x[1,2]x[4,3] - x[1,3]x[4,2], x[1,2]x[5,4] - x[1,4]x[5,2], x[2,4]x[5,5] - x[2,5]x[5,4], x[1,1]x[3,4] - x[1,4]x[3,1], x[2,3]x[6,5] - x[2,5]x[6,3] )***; /**/ Poincare(R/J); /**/ RJ := Radical(J);
Related issues
History
#1 Updated by Anna Maria Bigatti over 11 years ago
- Category set to Incomplete function
#2 Updated by John Abbott over 10 years ago
Here are two more problem cases with radical
Use ZZ/(2)[x,y,z]; I := ideal(x+y,x-y); radical(I);
Prints out some junk!
J := ideal(x^2 +y^2, x^2 +z^2, y^2 +z^2); radical(J);
Complains about an empty list of gens for an ideal.
Now that SqfreeFactor
has been implemented; it should be possible to fix radical
.
20140903 fixed
#3 Updated by John Abbott about 10 years ago
Here's an old(?) failing case; posting here so that we have a test suite.
Use R::=ZZ/(2)[a,b,c,d,e,f,g,h,i,j,k,l,m,n,o]; A:=Mat([ [0,a,b,c,d], [a,0,f,g,h], [b,f,0,j,k], [c,g,j,0,m], [d,h,k,m,0] ]); B:=Mat([ [0,f,g,h,i], [f,0,j,k,l], [g,j,0,m,n], [h,k,m,0,o], [i,l,n,o,0] ]); J:=Ideal(Minors(A,4))+Ideal(Minors(B,4)); JJ:=Radical(J); JJ;
20140121: in C5 gives error Empty List in ctor for ideal
20140903: fixed
#4 Updated by Anna Maria Bigatti almost 10 years ago
- Target version set to CoCoA-5.1.0 Easter14
#5 Updated by John Abbott almost 10 years ago
- Target version changed from CoCoA-5.1.0 Easter14 to CoCoA-5.1.1 Seoul14
#6 Updated by John Abbott almost 10 years ago
- Status changed from New to In Progress
- % Done changed from 0 to 10
- Estimated time set to 20.00 h
20140514 JAA confirms that the original problem persists; also gives numerous memory alloc errors like this:
CoCoAInterpreter(5397) malloc: *** error for object 0x101af8ba0: incorrect checksum for freed object - object was probably modified after being freed.
#7 Updated by John Abbott almost 10 years ago
Here is an excerpt from CoCoA (this morning, 20140624)
>>> I:=ideal(x*y-1,(x-2)^2+(y-2)^2-2); >>> ReducedGBasis(I); [x*y -1, x^2 +y^2 -4*x -4*y +6, y^3 -4*y^2 +x +6*y -4] >>> radical(I); ideal(x*y -1, x^2 +y^2 -4*x -4*y +6, x -1) >>> radical(I+ideal(z)); ideal(z, y -1, x -1)
20140625 Renzo pointed out that the result is correct but "poorly presented"; the result is indeed ideal(x-1,y-1)
20140903 this is a problem due to the output of GBasis (therefore intersect) for non-homogenous input
#8 Updated by Anna Maria Bigatti over 9 years ago
- Status changed from In Progress to Feedback
- Assignee set to Anna Maria Bigatti
- % Done changed from 10 to 90
found the bug: usual ref-count bug on RINGHOM.
Found a few more little bugs in the way ;-)
#9 Updated by Anna Maria Bigatti over 9 years ago
- Subject changed from Radical to Bug in Radical (actually a RingHom problem)
- Status changed from Feedback to Closed
- % Done changed from 90 to 100