significant performance drop for some examples

[jakobkroeker]

the following example drops performance significantly with your patches in comparison to recent singular spielwiese

// finishes in singular-spielwiese in a bit (correct or not?), but
// does not finish in reasonable time using SignatureSB
ring rng = integer,(x,y,z),dp;
option(redSB); option(redTail);
ideal J = -12xy-59xz+40x-22y2,
-109x-22y2z2-42,
69x2z-97x-115y-19;
ideal stdJ  = std(J);

in M2: (finishes in a bit)

# default is dp ordering:
rng = ZZ[x,y,z]
I = ideal(-12*x*y-59*x*z+40*x-22*y^ 2,-109*x-22*y^ 2*z^ 2-42,69*x^2*z-97*x-115*y-19)
groebnerBasis I

[adipopescu]

this is because of chain criterion. Over the integers, when activated it gives wrong results.

[adipopescu]

The same in this case. Compared M2 output with the singular. In this case M2 has 20 elements, Singular 21.

reduce(M2,Singular) = 0 reduce(Singular,M2) != 0 reduce(input, Singular) = 0 reduce(input, M2) = 0

lead(m); [1]=12xy [2]=13590361785xz2 [3]=2y2z [4]=69x2z [5]=391287546x3 [6]=27646102z4 [7]=649yz3 [8]=649xz3 [9]=y2z2 [10]=xyz2 [11]=23x2z2 [12]=3x2yz [13]=1688429402y4 [14]=2xy3 [15]=6x2y2 [16]=6x3y [17]=518949x4 [18]=x2z3 [19]=x2y2z [20]=3x4y

[1]=12xy [2]=13590361785xz2 [3]=2y2z [4]=69x2z [5]=391287546x3 [6]=27646102z4 [7]=649yz3 [8]=649xz3 [9]=y2z2 [10]=xyz2 [11]=23x2z2 [12]=3x2yz [13]=1688429402y4 [14]=2xy3 [15]=6x2y2 [16]=6x3y [17]=518949x4 [18]=x2z3 [19]=x2y2z [20]=3x4y _[21]=x4y3