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D.2.8.16 id2mod
Procedure from library poly.lib (see poly_lib).
- Usage:
- id2mod(I,vpos); I ideal, vpos intvec
- Return:
- module corresponding to the ideal by replacing var(vpos[i]) by
gen(i) and omitting all generators var(vpos[i])*var(vpos[j])
- Note:
- * This procedure only makes sense if the ideal contains
all var(vpos[i])*var(vpos[j]) as monomial generators and
all other generators of I are linear combinations of the
var(vpos[i]) over the ring in the other variables.
* This is the inverse procedure to mod2id and should be applied
only to ideals created by mod2id using the same intvec vpos
(possibly after a standard basis computation)
Example:
| LIB "poly.lib";
ring r=0,(e(1),e(2),x,y,z),(dp(2),ds(3));
ideal i=e(2)^2,e(1)*e(2),e(1)^2,e(1)*y+e(2)*x;
intvec iv=2,1;
id2mod(i,iv);
==> _[1]=x*gen(1)+y*gen(2)
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