Changes between Version 1 and Version 3 of Ticket #17696


Ignore:
Timestamp:
08/18/17 11:39:45 (4 years ago)
Author:
saraedum
Comment:

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  • Ticket #17696

    • Property Summary changed from bug in polynomial interface to Singular (in special rings) to Polynomials over fraction fields incorrectly converted to Singular
    • Property Stopgaps changed from to todo
  • Ticket #17696 – Description

    v1 v3  
    1 It seems that the interface to Singular has a bug,
    2 see example:
    31{{{
    4 sage: K0=GF(11)
    5 sage: #K0=QQ
    6 sage: R0.<b>=K0[]
    7 sage: K.<b>=K0.extension(b^5+4)
    8 sage: R1.<zzz>=K[]
    9 sage: L=FractionField(R1)
    10 sage: R.<x>=L[]
    11 sage: f=x^4+1/(b*zzz)
    12 sage: f._singular_()  #  where is the fraction 1/(b*zzz)  ?
     2sage: k.<a> = GF(11^5)
     3sage: R.<t> = k[]
     4sage: R.<x> = R.fraction_field()[]
     5sage: f = x^4 + 1/(a*t)
     6sage: f._singular_()
    137x^4
    14 sage: g = R(x^4)
    15 sage: f==g
    16 False
    17 
     8sage: g = x^4 + 1/a * 1/t
     9sage: f == g
     10True
     11sage: g._singular_()
     12x^4 + (6*a^4 + 5*a)/t
    1813}}}
    19 
    20 Note that already
    21 {{{
    22 sage: (1/(b*zzz))._singular_()
    23 0
    24 }}}
    25 
    26 Remarkable is that {{{f = x^4+1/(b)*(1/zzz) }}} is correctly translated to Singular:
    27 {{{
    28 sage: K0=GF(11)
    29 sage: #K0=QQ
    30 sage: R0.<b>=K0[]
    31 sage: K.<b>=K0.extension(b^5+4)
    32 sage: R1.<zzz>=K[]
    33 sage: L=FractionField(R1)
    34 sage: R.<x>=L[]
    35 sage: f=x^4+1/(b)*(1/zzz)
    36 sage: f._singular_()
    37 -1/(4*zzz)*b^4+x^4
    38 sage: g = -1/(4*zzz)*b^4+x^4
    39 sage: f == g
    40 True
    41 }}}
    42 
    43 Please check  if there is a similar issue in other rings than in the example above.
    44 
    45 @Simon, @Martin:
    46 should I Ccing someone else or remove you from Cc?
    47