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Strange result
https://www.singular.uni-kl.de/forum/viewtopic.php?f=10&t=1344		 Page 1 of 1
Author:  Carlos Bahiano [ Thu Aug 11, 2005 5:31 pm ]
Post subject:  Strange result
Dear singular team.
A friend had asked to me to eliminate the variables x and y from the ideal k below.
There is something wrong with Singular but I am not able to tell what it is. Look what i got, that is very strange because the same commands were used very well with others ideals.

> ring I = 0,(x,y,u,v,w),dp;
> I;
// characteristic : 0
// number of vars : 5
// block 1 : ordering dp
// : names x y u v w
// block 2 : ordering C

> option(prot);
Ø ideal j = u-xy,v-x4-y5,w+4x4-5y5;


> ideal k = u-x*y,v-x^4-y^5-x*y^2-x^3*y,w+4*x^4-5*y^5-x*y^2+2*x^3*y;

> eliminate (k,xy);
[63:3]2(2)s5ss6ss7(3)s-8-s9-ss10(5)s(6)-s(7)s(9)-s11(11)s(13)s(15)s(14)--s12
-s(15)s(18)s(21)---s---13-s(17)s(20)s(23)s(26)------s(23)--14-s(24)s(28)s(29
)sss(30)ss(32)s15s(35)s(36)-s(37)ss(39)s(42)s(45)s(47)s(50)s(52)s(55)s(58)s(
54)s(49)s(47)----s(45)s(48)------16-s(44)s(42)s(40)ss(42)---------------17-s
(29)s(32)s(35)s(37)s----------------18-s(23)s(26)s(28)-s(31)--s-----------19
-s(22)s(25)s-------------20-s(14)s(17)s(20)--------21-s(13)s(16)s(19)----s22
(17)ss(20)--------23-s(14)ss(16)s(18)-s(20)--24-ss(17)---s----25-s(12)s(15)s
(18)s(21)-s(23)--26-s(20)s(23)s(26)s(27)---s-s(26)s(28)Singular : signal 11
(v: 2003/2002030115):

Segment fault/Bus error occurred (r:1035481123)
please inform the authors
trying to restart...


What do you think ?
If i use the following the computation just carry on without errors but the answer is not what i expected.
ring r =(0,x,y),(z,u,v,w),dp;
// ** redefining r **
> r;
// characteristic : 0
// 2 parameter : x y
// minpoly : 0
// number of vars : 4
// block 1 : ordering dp
// : names z u v w
// block 2 : ordering C
> ideal I = u-x*y,v-x^4-y^5-x*y^2-x^3*y,w+4*x^4-5*y^5-x*y^2+2*x^3*y;
> help elim;
> eliminate(I,xy);
_[1]=w+(4x4+2x3y-xy2-5y5)
_[2]=v+(-x4-x3y-xy2-y5)
_[3]=u+(-xy)
> option(prot);
> eliminate(I,xy);
[255:3]1(2)sss
product criterion:3 chain criterion:0
_[1]=w+(4x4+2x3y-xy2-5y5)
_[2]=v+(-x4-x3y-xy2-y5)
_[3]=u+(-xy)

What is happening?

best wishes.
Carlos Bahiano.


email: [email protected]
Posted in old Singular Forum on: 2002-12-02 19:11:33+01
Author:  Hans Schönemann [ Wed Sep 21, 2005 8:34 pm ]
Post subject: 
> > ring I = 0,(x,y,u,v,w),dp;
> > ideal k = u-x*y,v-x^4-y^5-x*y^2-x^3*y,w+4*x^4-5*y^5-x*y^2+2*x^3*y;
>
> > eliminate (k,xy);
...
> Segment fault/Bus error occurred (r:1035481123)
> please inform the authors
> trying to restart...
You are probably out of memory in this case.
It is better to define the ring as
ring I=0,(x,y,u,v,w),(dp(2),dp);
ideal k=...
ideal kk=groebner(k);
and the the result are all polynomial of kk which do not contain
x and y.
--------------------------------------------------------
>
> If i use the following the computation just carry on without errors but the answer is not what i expected.
> ring r =(0,x,y),(z,u,v,w),dp;
...
> > eliminate(I,xy);
You cannot elimate paramters, only variables.

email: [email protected]
Posted in old Singular Forum on: 2003-04-16 11:13:15+02
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