I've been trying to run Macaulay2 in Sage to generate some examples for a project I have.
I used cloud.sagemath.com and everything worked fine for a while, but some inputs just wouldn't evaluate. There was no error, and it wouldn't freeze- it's just that nothing would happen. I figured there was a calculation limit, so I downloaded sage and Macaulay2, but the same problem occurs. Sage and Macaulay2 appear to be properly installed.
An example of code which doesn't do anything is:
R=ZZ[O1,O2,O3,O4,O5,In1,In2,In3,In4,In5];
I= ideal (O1O2,O2O3,O3O4,O4O5,O5O1,In1In3,In3In5,In5In2,In2In4,In4In1,O1In1,O2In2,O3In3,O4In4,O5*In5);
J= ideal (O1,O2,O3,O4,O5,In1,In2,In3,In4,In5);
v= flatten entries mingens J;
e=flatten entries mingens I;
m=table(e,e,(a,b)->a*b);
s= unique flatten m;
for i when i<length e="" do="" s="delete(e#i^2,s);</p">
dvds = (a,b) -> if b%(a*a)==0 then true else false;
f = x -> any(v, a -> dvds(a,x));
i=0; while i<#s do if f(s#i)==false then s=delete(s#i,s) else i=i+1;
F= ideal (s);
betti F
betti I
Meanwhile, similar code which returns correct-looking output is
%macaulay2
R=ZZ[x1,x2,x3,x4];
I= ideal (x1x2, x2x3, x3x4, x4x1);
J= ideal (x1,x2,x3,x4);
v= flatten entries mingens J;
e=flatten entries mingens I;
m=table(e,e,(a,b)->a*b);
s= unique flatten m;
for i when i<length e="" do="" s="delete(e#i^2,s);</p">
dvds = (a,b) -> if b%(a*a)==0 then true else false;
f = x -> any(v, a -> dvds(a,x));
i=0; while i<#s do if f(s#i)==false then s=delete(s#i,s) else i=i+1;
s
F= ideal (s);
betti F
betti I
The output is Ideal of R
Ideal of R
2 2 2 2
{x1x3x4 , x2x3 x4, x1 x2x4, x1*x2 x3}
List
Ideal of R
0 1
total: 1 4 0: 1 . 1: . . 2: . . 3: . 4
BettiTally
0 1
total: 1 4 0: 1 . 1: . 4
BettiTally
The only real difference seems to be the number of calculations made, and this idea is confirmed in that the calculations always seem to fail around ZZ[x1..xn] for n>8. There must be some way to fix this. Can anyone help?