Opened 12 years ago

Closed 12 years ago

#295 closed bug (fixed)

Wrong 'preimage' documentation (note)

Reported by: lars.kastner@… Owned by: hannes
Priority: minor Milestone: 3-1-3 and higher
Component: doc Version:
Keywords: preimage Cc:

Description (last modified by Oleksandr )

preimage documentation: ([www.singular.uni-kl.de/Manual/latest/sing_277.htm#SEC317])

As preimage is handling ideals (not polynomials), the result of a preimage calculation of a principal ideal, whose generator is not in the image of the map, is the zero ideal.

I suggest removing this Note from the preimage documentation page.

ring r = 0,(x),dp;
ring q = 0,(a),dp;
map f = r, a^2;
ideal i = a;
setring r;
preimage(q,f,i);

This returns the ideal (x) in k[x] and contradicts the note from above.

Lars

Change History (3)

comment:1 Changed 12 years ago by Oleksandr

Component: dontKnowdoc
Description: modified (diff)
Keywords: preimage added
Summary: preimage NoteWrong 'preimage' documentation (note)
Version: 3-1-2

comment:2 Changed 12 years ago by seelisch

Owner: changed from somebody to hannes

comment:3 Changed 12 years ago by hannes

Resolution: fixed
Status: newclosed

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