Ilya Zakharevich on Fri, 2 Nov 2001 18:50:33 -0500 |
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Re: subst() broken |
On Sat, Nov 03, 2001 at 12:31:02AM +0100, Bill Allombert wrote: > > > Probably you mean (1+y)*Mod(1,z), but it is not the same thing: > > > it is a polynomial not a POLMOD. > > I have no slightest idea what you mean by this sentence. Can it be > > expressed algebraically, or it is just some "implementation detail"? > Both. [Can't understand your examples, but I hope one can replace Z by Z^3 to get something more friendly.] > (1+y)*Mod(1,z) is an object living in the ring (Q[Z]/(Z))[Y], > so it is a polynomial in Y whose coeffcients are cosets in Z. You mean the coefficients are in Q[Z]/(Z) == Z? > Mod(1+y,z) is an object living in Q(Z)[Y]/(Z) so it is a coset, > but the ideal (Z) being trivial because Z is invertible, this quotient > is the null ring. The next question is how I can deduce that these expressions will result in elements of these rings. [Preferably deduce basing on the documentation. ;-] Ilya