#12170: Genus computation (using singular) and _singular_ object for function
filed
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Reporter: sydahmad | Owner: AlexGhitza
Type: enhancement | Status: needs_work
Priority: minor | Milestone: sage-5.0
Component: algebraic geometry | Keywords: function field, genus,
singular
Work_issues: | Upstream: N/A
Reviewer: | Author: Syed Ahmad Lavasani
Merged: | Dependencies: #9054
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Changes (by saraedum):
* status: needs_review => needs_work
Comment:
I'm surprised myself but singular does not complain about fractions:
{{{
sage: singular.ideal('y^5 - (x^3 + 2*x*y + 1/x)')
-x^3-2*x*y+y^5
sage: singular.eval('1/x')
0
}}}
The 1/x was just thrown out because in singular it evaluates to 0. Anyway
I think you're maybe doing too many direct calls to singular. Why not go
to the polynomial ring QQ[x,y] create the ideal there get its singular
object and determine the genus in singular? Or maybe I misunderstand what
the genus function in singular does.
Also, is_RationalFunctionField() should imho be a member method
is_rational() of FunctionField that is overwritten in
RationalFunctionField and FunctionField_polymod.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12170#comment:7>
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