Category of number field morphisms is always Rings

[saraedum]

In the following example, the category should be NumberFields()

sage: R.<x> = QQ[]
sage: K.<a> = QQ.extension(x^2 + 1)
sage: K.hom([a]).category_for()
Category of rings

CC: @roed314 @xcaruso

Component: number fields

Author: Julian Rüth

Branch: 07936de

Reviewer: David Roe

Issue created by migration from https://trac.sagemath.org/ticket/22001

[saraedum]

Branch: u/saraedum/category_of_number_field_morphisms_is_always_rings

[saraedum]

comment:2

Why would we ignore the cat keyword? Maybe category support was not that great at the time? Let's see what the patchbot thinks.

[saraedum]

Changed branch from u/saraedum/category_of_number_field_morphisms_is_always_rings to none

[saraedum]

comment:3

Btw. the comment that it is ignored was introduced in

commit 2cda3cde81efa0b5546e60170bee7ae084263a4f
Author: William Stein <[email protected]>
Date:   Sun Sep 16 23:02:21 2007 -0700

    work in progress on algebraic number theory.

so there is no further info on this.

[roed314]

Commit: 2d2818f

[roed314]

comment:5

It looks like you deleted the branch when you set it to needs review. I'm putting the branch back, but if there's something wrong with the branch let me know.

---

New commits:

2d2818f

Do not ignore the cat keyword of number field morphisms

[roed314]

Branch: u/saraedum/category_of_number_field_morphisms_is_always_rings

[roed314]

Reviewer: David Roe

[roed314]

comment:6

Looks good to me.

[vbraun]

comment:7

See patchbot:
sage -t --long --warn-long 53.9 src/sage/schemes/projective/projective_morphism.py # 2 doctests failed

[sagetrac-git]

Changed commit from 2d2818f to 07936de

[sagetrac-git]

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

07936de

A morphism of a number field is a morphism of a ring and vice versa

[saraedum]

New commits:

07936de

A morphism of a number field is a morphism of a ring and vice versa

---

New commits:

07936de

A morphism of a number field is a morphism of a ring and vice versa

[roed314]

comment:10

Do you know why self.homset_category().is_full_subcategory(x.category_for()) returns False?

[saraedum]

comment:11

It is mentioned here: https://github.com/sagemath/sage-prod/blob/master/src/sage/categories/category.py#L1299

[saraedum]

comment:12

The failing doctest is some latex issue of the patchbot. I don't think it is related to the changes here.

[roed314]

comment:13

Looks good, and patchbot says all tests pass.

[vbraun]

Changed branch from u/saraedum/category_of_number_field_morphisms_is_always_rings to 07936de

[jdemeyer]

comment:15

See #23910 for relative number field homsets.

[jdemeyer]

Changed commit from 07936de to none