Dear Sage Community,
I havnt been using Sage that long but iv noticed a trend, in that my
sage doesnt seem to complete some more difficult tasks. Either it
completes the task in less than 10 seconds or it doesnt complete it
all! It feels like once I have crossed a certain threshold the
computation will never finish and I have to interupt it.

Here is my spec:
OS: Windows XP (latest version)
Sage Version: SAGE Version 3.0.1, Release Date: 2008-05-05
Using firefox notebook through VMware player.
Machine: 2.40GHz, 1.97Gb RAM, Plently of free Hard disk space.

As an example, iv been trying to compute the following Groebner Bases
(apologises for the code overload! I wasnt sure how else to present
it...)

----------------------------------------------------------------------------------------------------------------------------------------------------------------

R.<x0,x1,x2,x3,x4,x5,x6,R10,R11,R12,R13,R14,R15,R16,R17,R18,R19,R110,R111,R112,R113,R114,R115>
=PolynomialRing(QQ);

I=ideal([-x4*R14 - x6*R16 + x6*R17 + x5*R19 + x3*R113,x5*R11 + x2*R14
+ x4*R17
- x3*R110 + x6*R112, -x6*R11 - x2*R12 - x2*R16 + x1*R17 + x6*R18 +
x1*R110 - x3*R115 - x4*R115, -x5*R11 - x4*R12 - x2*R14 + x3*R16 -
x4*R17
+ x5*R18 + x6*R19 + x3*R110 + x1*R113 + x6*R115, -x6*R11 - x2*R12 +
x6*R13 + x0*R14 + x5*R15 - x2*R16 + x1*R110 - x3*R114 - x4*R115,x0*R12
- x3*R13 - x4*R13 + x6*R15 + x0*R16 + x4*R18 - x1*R112 - x1*R114],R);

len(I.gens());
  6

len(I.groebner_basis());
  30

(calculated in less than 3 seconds)


However if I add just one more generator it never completes the
computation:

J=ideal([-x4*R14 - x6*R16 + x6*R17 + x5*R19 + x3*R113,x5*R11 + x2*R14
+ x4*R17
- x3*R110 + x6*R112, -x6*R11 - x2*R12 - x2*R16 + x1*R17 + x6*R18 +
x1*R110 - x3*R115 - x4*R115, -x5*R11 - x4*R12 - x2*R14 + x3*R16 -
x4*R17
+ x5*R18 + x6*R19 + x3*R110 + x1*R113 + x6*R115, -x6*R11 - x2*R12 +
x6*R13 + x0*R14 + x5*R15 - x2*R16 + x1*R110 - x3*R114 - x4*R115,x0*R12
- x3*R13 - x4*R13 + x6*R15 + x0*R16 + x4*R18 - x1*R112 - x1*R114,
x3*R10 - x4*R10 + x3*R11 + x0*R17 - x2*R19 + x0*R110 + x6*R111 -
x2*R112 - x2*R114],R);

len(J.gens());
  7

len(J.groebner_basis());
  ?

I actually want to calculate the groebner basis for the following
ideal:
K=ideal([-x4*R14 - x6*R16 + x6*R17 + x5*R19 + x3*R113, x5*R11 + x2*R14
+ x4*R17
- x3*R110 + x6*R112, -x6*R11 - x2*R12 - x2*R16 + x1*R17 + x6*R18 +
x1*R110 - x3*R115 - x4*R115, -x5*R11 - x4*R12 - x2*R14 + x3*R16 -
x4*R17
+ x5*R18 + x6*R19 + x3*R110 + x1*R113 + x6*R115, -x6*R11 - x2*R12 +
x6*R13 + x0*R14 + x5*R15 - x2*R16 + x1*R110 - x3*R114 - x4*R115,
x0*R12
- x3*R13 - x4*R13 + x6*R15 + x0*R16 + x4*R18 - x1*R112 - x1*R114,
-x3*R10 - x4*R10 + x3*R11 + x0*R17 - x2*R19 + x0*R110 + x6*R111 -
x2*R112 - x2*R114, x6*R10 - x6*R11 - x2*R16 + x5*R111 + x0*R113 -
x4*R114, -x1*R10 + x1*R11 + x2*R13 + x4*R15 - x2*R18 + x0*R19 -
x3*R111
+ x0*R115, -x3*x6*R10 + x3*x6*R11 + x0*x6*R12 - x3*x6*R13 + x4*x5*R15
+
x6^2*R15 + x2*x3*R16 - x1*x4*R17 + x0*x6*R17 + x0*x5*R19 - x3*x5*R111
-
x1*x6*R112 - x1*x6*R114 + x3*x4*R115, -x3^2*R10 - x3*x4*R10 + x3^2*R11
+
x0*x5*R11 - x2*x6*R13 - x2*x5*R15 + x1*x2*R17 + x0*x3*R17 + x0*x4*R17
+
x2*x6*R18 - x2*x3*R19 + x3*x6*R111 - x2*x3*R112 + x0*x6*R112 -
x2*x3*R115, x1*x4*R11 - x0*x6*R11 + x3*x4*R15 + x4^2*R15 + x2*x6*R15 -
x2*x3*R18 + x0*x6*R18 + x1*x2*R19 + x0*x3*R19 + x0*x4*R19 - x3^2*R111
-
x3*x4*R111 - x1*x6*R111, -x0*x3*x6^2*R12 - x0*x4*x6^2*R12 +
x3^2*x6^2*R13 + x3*x4*x6^2*R13 - x2*x6^3*R13 - x3*x6^3*R15 -
x4*x6^3*R15
+ x1*x2*x6^2*R16 - x3*x4*x6^2*R18 + x0*x5*x6^2*R18 + x2*x6^3*R18 -
x1*x5*x6^2*R111 + x3*x6^3*R111 + x1*x3*x6^2*R112 + x0*x6^3*R112 +
x1*x3*x6^2*R114 + x1*x4*x6^2*R114],R);

len(K.gens());
 13

Seems a long way off....


Am I really pushing Sage beyond its limits or is there something else
more subtle going on?

Thanks!
Dan


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