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factorize allowed in qrings? #116

Open jakobkroeker opened 9 years ago

jakobkroeker commented 9 years ago

are qrings allowed for factorize()?

ring rng = 0,(x,b),lp;
short = 0;
qring qr =b^2-2;
poly f = x^2-2;
factorize(f); // expected: (x-b)*(x+b) ?
[1]:
   _[1]=1
   _[2]=x^2-2
[2]:
   1,1

our minAssGTZX (not in Singular yet) obtains

[1]
   _[1]=x^2-2
   _[2]=b+x
[2]
   _[1]=x^2-2
   _[2]=b-x
jakobkroeker commented 9 years ago

Hans improved the documentation; https://github.com/Singular/Sources/commit/d0a684deae0e95680bb1a9034bac826e37c75368

jakobkroeker commented 9 years ago

is the documentation improvement by Hans (https://github.com/Singular/Sources/commit/d0a684deae0e95680bb1a9034bac826e37c75368) sufficient for users (of 'factorize')?

fruhbis-kruger-anne commented 9 years ago

The improved documentation is sufficient for reminding users that they are dealing with residue classes instead of polynomials.

Personally, I would still prefer to forbid factorize in qrings, as e.g. QQ[x,y,z]/ is not a UFD.

jakobkroeker commented 9 years ago

The improved documentation is sufficient for reminding users that they are dealing with residue classes instead of polynomials.

I think, it is only sufficient if factory (and other affected function) links to this general statement; see also http://www.singular.uni-kl.de:8002/trac/ticket/699