make NumberFieldFractionalIdeal inherit from Ideal_fractional

[yyyyx4]

We have an Ideal_fractional parent class, but the most important type of fractional ideals in Sage (namely, for number fields) does not inherit from it. Let's change this, so that we can reliably distinguish fractional ideals from ideals.

(I haven't found any other fractional ideals in Sage that are not already children of Ideal_fractional.)

This patch should result in absolutely no change in behaviour, except that isinstance(I, Ideal_fractional) now returns True when I is a NumberFieldFractionalIdeal.

Component: number fields

Keywords: fractional ideals

Author: Lorenz Panny

Branch/Commit: 55cfe14

Reviewer: Frédéric Chapoton

Issue created by migration from https://trac.sagemath.org/ticket/32380

[fchapoton]

comment:2

needs a doctest

[sagetrac-git]

Changed commit from aa898ad to 8039ce4

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

8039ce4

add doctest for #32380

[yyyyx4]

comment:4

Done.

[fchapoton]

comment:5

ok

[fchapoton]

Reviewer: Frédéric Chapoton

[vbraun]

comment:6

Merge conflict

[sagetrac-git]

Changed commit from 8039ce4 to 65805c5

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

65805c5

Merge tag '9.5.beta3' into public/make_NumberFieldFractionalIdeal_inherit_from_Ideal_fractional

[yyyyx4]

comment:8

Thanks, fixed.

[tscrim]

comment:9

One (seems trivial) failing doctest according to the patchbot:

sage -t --long --random-seed=43805222569518434108329399959452339425 src/sage/rings/polynomial/polynomial_element_generic.py
**********************************************************************
File "src/sage/rings/polynomial/polynomial_element_generic.py", line 783, in sage.rings.polynomial.polynomial_element_generic.Polynomial_generic_sparse.quo_rem
Failed example:
    f.quo_rem(g)
Expected:
    Traceback (most recent call last):
    ...
    ArithmeticError: Division non exact (consider coercing to polynomials over the fraction field)
Got:
    (-y^5 + 2*y^2, y^3 - 2*x^2*y^2 - y)
**********************************************************************

So some functionality is apparently changed for something that did not work before but now gives a result. Seems like a good thing.

[yyyyx4]

comment:10

Some quick testing suggests the failure is random (unrelated to this ticket, in any case). I've opened #32816 for this.

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

55cfe14

Merge tag '9.5.beta5' into public/make_NumberFieldFractionalIdeal_inherit_from_Ideal_fractional

[sagetrac-git]

Changed commit from 65805c5 to 55cfe14

[tscrim]

comment:12

Thanks. Then I am setting this back to a positive review.

[yyyyx4]

comment:13

Thank you!

[vbraun]

Changed branch from public/make_NumberFieldFractionalIdeal_inherit_from_Ideal_fractional to 55cfe14