Hi Oleksandr,
On 16 Feb., 17:58, Oleksandr Kazymyrov <vrona.aka.ham...@gmail.com>
wrote:
> I am forcing the call of a function
> pol.mod(P("y^8+y")) to obtain the remainder by modulus.
Sorry, I had missed that (the example was quite long, and thus I had
the impression that you had merely constructed a polynomial over a
finite field, but no modulus except the modulus of the finite field).
> And I expect that
> monomial "y^10*a2*b1^10*p5^2" will has degree 3 (y^3*a2*b1^10*p5^2) after
> operation pol.mod(P("y^8+y")) in the polynomial.
Right. That sounds like a bug to me.
Starting with your definitions, it seems to me that the bug is in
libSingular (which is used for polynomial arithmetic in Sage), whereas
Singular itself computes it correctly:
sage: polS = singular(pol)
sage: IS = singular(I)
sage: singular("NF(%s,std(%s))"%(polS.name(), IS.name()))
y^7*a2*b1^14*p7^2+y^7*a2*b2^14*p7^2+y^6*a2*b0^8*b1^6*p7^2+y^6*a2*b1^8*b2^6*p7^2+y^6*a2*b0^2*b1^4*b2^8*p7^2+y^6*a2*b0^4*b2^10*p7^2+y^5*a2*b0^2*b1^12*p7^2+y^5*a2*b0^4*b1^8*b2^2*p7^2+y^5*a2*b0^8*b2^6*p7^2+y^5*a2*b1^2*b2^12*p7^2+y^6*a2*b1^4*b2^8*p6^2+y^4*a2*b0^10*b1^4*p7^2+y^4*a2*b0^12*b2^2*p7^2+y^4*a2*b1^10*b2^4*p7^2+y^4*a2*b0^4*b1^2*b2^8*p7^2+y^5*a2*b1^12*p6^2+y^3*a2*b0^4*b1^10*p7^2+y^3*a2*b0^8*b1^2*b2^4*p7^2+y^3*a2*b1^4*b2^10*p7^2+y^3*a2*b0^2*b2^12*p7^2+y^6*a2*b2^10*p5^2+y^4*a2*b0^8*b1^4*p6^2+y^2*a2*b0^12*b1^2*p7^2+y^2*a2*b1^12*b2^2*p7^2+y^2*a2*b0^2*b1^8*b2^4*p7^2+y^2*a2*b0^6*b2^8*p7^2+y^5*a2*b1^8*b2^2*p5^2+y^3*a2*b2^12*p6^2+y*a2*b0^6*b1^8*p7^2+y*a2*b0^8*b1^4*b2^2*p7^2+y*a2*b0^10*b2^4*p7^2+y*a2*b1^6*b2^8*p7^2+y^4*a2*b0^8*b2^2*p5^2+y^4*a2*b1^2*b2^8*p5^2+y^2*a2*b1^8*b2^4*p6^2+y^2*a2*b0^4*b2^8*p6^2+a2*b0^14*p7^2+y^3*a2*b1^10*p5^2+y*a2*b0^4*b1^8*p6^2+y*a2*b0^8*b2^4*p6^2+y^7*a1*b1^7*p7+y^7*a1*b2^7*p7+y^6*a2*b1^6*p3^2+y^2*a2*b0^8*b1^2*p5^2+y^2*a2*b0^2*b2^8*p5^2+a2*b0^12*p6^2+y^6*a1*b0*b1^6*p7+y^6*a1*b0^2*b1^4*b2*p7+y^6*a1*b0^4*b2^3*p7+y^6*a1*b1*b2^6*p7+y^5*a2*b2^6*p3^2+y*a2*b0^2*b1^8*p5^2+y^6*a1*b1^6*p6+y^5*a1*b0^2*b1^5*p7+y^5*a1*b0^4*b1*b2^2*p7+y^5*a1*b1^2*b2^5*p7+y^5*a1*b0*b2^6*p7+y^4*a2*b0^2*b1^4*p3^2+y^4*a2*b0^4*b2^2*p3^2+y^2*a2*b2^8*p4^2+y^6*a1*b1^4*b2*p5+a2*b0^10*p5^2+y^5*a1*b2^6*p6+y^4*a1*b0^3*b1^4*p7+y^4*a1*b0^4*b1^2*b2*p7+y^4*a1*b0^5*b2^2*p7+y^4*a1*b1^3*b2^4*p7+y^3*a2*b1^2*b2^4*p3^2+y*a2*b1^8*p4^2+y^5*a1*b1^5*p5+y^4*a1*b0^2*b1^4*p6+y^4*a1*b0^4*b2^2*p6+y^3*a1*b0^4*b1^3*p7+y^3*a1*b1^4*b2^3*p7+y^3*a1*b0*b1^2*b2^4*p7+y^3*a1*b0^2*b2^5*p7+y^4*a2*b1^4*p2^2+y^6*a1*b2^3*p3+y^2*a2*b0^4*b1^2*p3^2+a2*b0^8*p4^2+y^4*a1*b0*b1^4*p5+y^3*a1*b1^2*b2^4*p6+y^2*a1*b0^5*b1^2*p7+y^2*a1*b0^6*b2*p7+y^2*a1*b1^5*b2^2*p7+y^2*a1*b0^2*b1*b2^4*p7+y^5*a1*b1*b2^2*p3+y*a2*b1^4*b2^2*p3^2+y*a2*b0^2*b2^4*p3^2+y^4*a1*b1^4*p4+y^3*a1*b2^5*p5+y^2*a1*b0^4*b1^2*p6+y*a1*b0^6*b1*p7+y*a1*b1^6*b2*p7+y*a1*b0*b1^4*b2^2*p7+y*a1*b0^3*b2^4*p7+y^4*a2*b2^2*p1^2+y^4*a1*b1^2*b2*p3+y^4*a1*b0*b2^2*p3+a2*b0^6*p3^2+y^2*a1*b0^4*b2*p5+y^2*a1*b1*b2^4*p5+y*a1*b1^4*b2^2*p6+y*a1*b0^2*b2^4*p6+a1*b0^7*p7+y^4*a1*b2^2*p2+y*a2*b2^4*p2^2+y^3*a1*b1^3*p3+y*a1*b0^4*b1*p5+y*a1*b0*b2^4*p5+a1*b0^6*p6+y^2*a2*b1^2*p1^2+a2*b0^4*p2^2+y^2*a1*b0*b1^2*p3+y^2*a1*b0^2*b2*p3+y*a1*b2^4*p4+a1*b0^5*p5+y^2*a1*b1^2*p2+y*a1*b0^2*b1*p3+a1*b0^4*p4+y^2*a1*b2*p1+a2*b0^2*p1^2+a1*b0^3*p3+y*a1*b1*p1+a1*b0^2*p2+y^2*c2+a2*p0^2+a1*b0*p1+y*c1+a1*p0+a0
sage: pol.reduce(I)
y^7*a2*b1^14*p7^2 + y^7*a2*b2^14*p7^2 + y^10*a2*b1^10*p5^2 +
y^8*a2*b0^4*b1^8*p6^2 + y^8*a2*b0^8*b2^4*p6^2 + y^14*a1*b2^7*p7 +
y^6*a2*b0^8*b1^6*p7^2 + y^6*a2*b1^8*b2^6*p7^2 +
y^6*a2*b0^2*b1^4*b2^8*p7^2 + y^6*a2*b0^4*b2^10*p7^2 +
y^9*a2*b0^2*b2^8*p5^2 + y^13*a1*b1*b2^6*p7 + y^5*a2*b0^2*b1^12*p7^2 +
y^5*a2*b0^4*b1^8*b2^2*p7^2 + y^5*a2*b0^8*b2^6*p7^2 +
y^5*a2*b1^2*b2^12*p7^2 + y^12*a2*b2^6*p3^2 + y^8*a2*b0^2*b1^8*p5^2 +
y^6*a2*b1^4*b2^8*p6^2 + y^12*a1*b1^2*b2^5*p7 + y^12*a1*b0*b2^6*p7 +
y^4*a2*b0^10*b1^4*p7^2 + y^4*a2*b0^12*b2^2*p7^2 +
y^4*a2*b1^10*b2^4*p7^2 + y^4*a2*b0^4*b1^2*b2^8*p7^2 + y^9*a2*b2^8*p4^2
+ y^12*a1*b2^6*p6 + y^5*a2*b1^12*p6^2 + y^11*a1*b1^3*b2^4*p7 +
y^3*a2*b0^4*b1^10*p7^2 + y^3*a2*b0^8*b1^2*b2^4*p7^2 +
y^3*a2*b1^4*b2^10*p7^2 + y^3*a2*b0^2*b2^12*p7^2 +
y^10*a2*b1^2*b2^4*p3^2 + y^8*a2*b1^8*p4^2 + y^6*a2*b2^10*p5^2 +
y^4*a2*b0^8*b1^4*p6^2 + y^10*a1*b1^4*b2^3*p7 + y^10*a1*b0*b1^2*b2^4*p7
+ y^10*a1*b0^2*b2^5*p7 + y^2*a2*b0^12*b1^2*p7^2 +
y^2*a2*b1^12*b2^2*p7^2 + y^2*a2*b0^2*b1^8*b2^4*p7^2 +
y^2*a2*b0^6*b2^8*p7^2 + y^5*a2*b1^8*b2^2*p5^2 + y^10*a1*b1^2*b2^4*p6 +
y^3*a2*b2^12*p6^2 + y^9*a1*b1^5*b2^2*p7 + y^9*a1*b0^2*b1*b2^4*p7 +
y*a2*b0^6*b1^8*p7^2 + y*a2*b0^8*b1^4*b2^2*p7^2 + y*a2*b0^10*b2^4*p7^2
+ y*a2*b1^6*b2^8*p7^2 + y^8*a2*b1^4*b2^2*p3^2 + y^8*a2*b0^2*b2^4*p3^2
+ y^10*a1*b2^5*p5 + y^4*a2*b0^8*b2^2*p5^2 + y^4*a2*b1^2*b2^8*p5^2 +
y^2*a2*b1^8*b2^4*p6^2 + y^2*a2*b0^4*b2^8*p6^2 + y^8*a1*b1^6*b2*p7 +
y^8*a1*b0*b1^4*b2^2*p7 + y^8*a1*b0^3*b2^4*p7 + a2*b0^14*p7^2 +
y^9*a1*b1*b2^4*p5 + y^8*a1*b1^4*b2^2*p6 + y^8*a1*b0^2*b2^4*p6 +
y^7*a1*b1^7*p7 + y^8*a2*b2^4*p2^2 + y^6*a2*b1^6*p3^2 +
y^8*a1*b0*b2^4*p5 + y^2*a2*b0^8*b1^2*p5^2 + a2*b0^12*p6^2 +
y^6*a1*b0*b1^6*p7 + y^6*a1*b0^2*b1^4*b2*p7 + y^6*a1*b0^4*b2^3*p7 +
y^8*a1*b2^4*p4 + y^6*a1*b1^6*p6 + y^5*a1*b0^2*b1^5*p7 +
y^5*a1*b0^4*b1*b2^2*p7 + y^4*a2*b0^2*b1^4*p3^2 + y^4*a2*b0^4*b2^2*p3^2
+ y^6*a1*b1^4*b2*p5 + a2*b0^10*p5^2 + y^4*a1*b0^3*b1^4*p7 +
y^4*a1*b0^4*b1^2*b2*p7 + y^4*a1*b0^5*b2^2*p7 + y^5*a1*b1^5*p5 +
y^4*a1*b0^2*b1^4*p6 + y^4*a1*b0^4*b2^2*p6 + y^3*a1*b0^4*b1^3*p7 +
y^4*a2*b1^4*p2^2 + y^6*a1*b2^3*p3 + y^2*a2*b0^4*b1^2*p3^2 +
a2*b0^8*p4^2 + y^4*a1*b0*b1^4*p5 + y^2*a1*b0^5*b1^2*p7 +
y^2*a1*b0^6*b2*p7 + y^5*a1*b1*b2^2*p3 + y^4*a1*b1^4*p4 +
y^2*a1*b0^4*b1^2*p6 + y*a1*b0^6*b1*p7 + y^4*a2*b2^2*p1^2 +
y^4*a1*b1^2*b2*p3 + y^4*a1*b0*b2^2*p3 + a2*b0^6*p3^2 +
y^2*a1*b0^4*b2*p5 + a1*b0^7*p7 + y^4*a1*b2^2*p2 + y^3*a1*b1^3*p3 +
y*a1*b0^4*b1*p5 + a1*b0^6*p6 + y^2*a2*b1^2*p1^2 + a2*b0^4*p2^2 +
y^2*a1*b0*b1^2*p3 + y^2*a1*b0^2*b2*p3 + a1*b0^5*p5 + y^2*a1*b1^2*p2 +
y*a1*b0^2*b1*p3 + a1*b0^4*p4 + y^2*a1*b2*p1 + a2*b0^2*p1^2 +
a1*b0^3*p3 + y*a1*b1*p1 + a1*b0^2*p2 + y^2*c2 + a2*p0^2 + a1*b0*p1 +
y*c1 + a1*p0 + a0
The strange thing is that everything is alright if just the single
monomial is considered:
sage: singular("NF(y^10*a2*b1^10*p5^2,std(%s))"%(IS.name()))
y^3*a2*b1^10*p5^2
sage: P('y^10*a2*b1^10*p5^2').reduce(I)
y^3*a2*b1^10*p5^2
sage: I.reduce(P('y^10*a2*b1^10*p5^2'))
y^3*a2*b1^10*p5^2
Do you have a trac account, or shall I open a trac ticket myself?
Best regards,
Simon
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