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qring inside qring
https://www.singular.uni-kl.de/forum/viewtopic.php?f=10&t=1668		 Page 1 of 1
Author:  hsuess [ Fri Apr 18, 2008 1:25 pm ]
Post subject:  qring inside qring
Hello,

a call of qring inside a qring results in a quotient of a polynomial ring by the new ideal, but the old one gets lost:

> ring r=0,(x,y),dp;
> qring qr=std(x^2);
> basering;
// characteristic : 0
// number of vars : 2
// block 1 : ordering dp
// : names x y
// block 2 : ordering C
// quotient ring from ideal
_[1]=x2
> qring qqr=std(y^2);
> basering;
// characteristic : 0
// number of vars : 2
// block 1 : ordering dp
// : names x y
// block 2 : ordering C
// quotient ring from ideal
_[1]=y2

as a solution I suggest a improved version of qring:

proc quotientRing(ideal I){
def @r=basering;
list rl=ringlist(@r);
list rl2=rl;
rl2[4]=ideal(0);
def @rr=ring(rl2);
setring @rr;
ideal I=imap(@r,I);
list rl=imap(@r,rl);
I=I+rl[4];
I=std(I);
rl[4]=I;
def @rrr=ring(rl);
return(@rrr);
}

best regards

Hendrik Suess
Author:  motsak [ Wed Apr 23, 2008 12:25 pm ]
Post subject:  Re: qring inside qring
Dear Hendrik Suess,

thanks for Your note.

This behaviour has been recently fixed.

Best regards,
Oleksandr Motsak
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