#15865: Should there be a method on a rational function field that returns the
ring
it came from?
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Reporter: darij | Owner:
Type: defect | Status: new
Priority: major | Milestone:
Component: algebra | Keywords: polynomials, fraction field,
Merged in: | categories
Reviewers: | Authors:
Work issues: | Report Upstream: N/A
Commit: | Branch:
Stopgaps: | Dependencies:
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If I have a fraction field, how do I find the ring whose fraction field it
is? Note that, since a fraction field sometimes serves several base rings
at the same time, this can mean:
- the base ring from which the fraction field was constructed (possibly
thread-unsafe?);
- a "canonical" base ring for which the fraction field can be constructed;
- or anything inbetween.
I'm not sure which of these are feasible; I'd be happy with a method that
returns me a polynomial ring if I apply it to the fraction field of said
polynomial ring. There is the `_base` attribute which seems to give the
base ring, but I'd prefer an exposed method.
I assume this also does the trick:
{{{
sage: g = FractionField(PolynomialRing(QQ, ['x']))
sage: parent(g.zero().numerator())
Rational Field
}}}
but it feels like a hack...
--
Ticket URL: <http://trac.sagemath.org/ticket/15865>
Sage <http://www.sagemath.org>
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