id summary reporter owner description type status priority milestone component resolution keywords cc merged author reviewer upstream work_issues branch commit dependencies stopgaps
15865 Should there be a method on a rational function field that returns the ring it came from? darij "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..." defect new major algebra polynomials, fraction field, categories tscrim sage-combinat N/A