Changes between Version 1 and Version 3 of Ticket #17696
 Timestamp:
 08/18/17 11:39:45 (4 years ago)
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Ticket #17696

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Summary
changed from
bug in polynomial interface to Singular (in special rings)
toPolynomials over fraction fields incorrectly converted to Singular

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Stopgaps
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to
todo

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Summary
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Ticket #17696 – Description
v1 v3 1 It seems that the interface to Singular has a bug,2 see example:3 1 {{{ 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) ? 2 sage: k.<a> = GF(11^5) 3 sage: R.<t> = k[] 4 sage: R.<x> = R.fraction_field()[] 5 sage: f = x^4 + 1/(a*t) 6 sage: f._singular_() 13 7 x^4 14 sage: g = R(x^4) 15 sage: f==g 16 False 17 8 sage: g = x^4 + 1/a * 1/t 9 sage: f == g 10 True 11 sage: g._singular_() 12 x^4 + (6*a^4 + 5*a)/t 18 13 }}} 19 20 Note that already21 {{{22 sage: (1/(b*zzz))._singular_()23 024 }}}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=QQ30 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^438 sage: g = 1/(4*zzz)*b^4+x^439 sage: f == g40 True41 }}}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