Opened 6 years ago
Closed 5 years ago
#23186 closed enhancement (fixed)
ZZ → QQ is not onto
| Reported by: | Julian Rüth | Owned by: | |
|---|---|---|---|
| Priority: | minor | Milestone: | sage-8.0 |
| Component: | commutative algebra | Keywords: | sd86.5 |
| Cc: | Merged in: | ||
| Authors: | Julian Rüth | Reviewers: | Travis Scrimshaw |
| Report Upstream: | N/A | Work issues: | |
| Branch: | 79fd62a (Commits, GitHub, GitLab) | Commit: | 79fd62a8c40632891cf32502a3d80709edc68cf8 |
| Dependencies: | Stopgaps: |
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Description (last modified by )
Currently, this fails
sage: QQ.coerce_map_from(ZZ).is_surjective() NotImplementedError
To fix this, we make the coercion morphism know it is not surjective.
Change History (6)
comment:1 Changed 6 years ago by
comment:3 Changed 6 years ago by
| Branch: | → u/saraedum/zz___qq_is_not_onto |
|---|
comment:4 Changed 6 years ago by
| Authors: | → Julian Rüth |
|---|---|
| Branch: | u/saraedum/zz___qq_is_not_onto |
| Status: | new → needs_review |
comment:5 Changed 6 years ago by
| Branch: | → u/saraedum/zz___qq_is_not_onto |
|---|---|
| Commit: | → 79fd62a8c40632891cf32502a3d80709edc68cf8 |
| Description: | modified (diff) |
| Reviewers: | → Travis Scrimshaw |
| Status: | needs_review → positive_review |
Because to do something at the category level, you should be doing something for all objects in that category, not for one specific object (in a specific implementation). Now, if you wanted to have something in Rings checking if a morphism to ZZ was surjective returning True, then that would be good because it is true for all rings (of characteristic 0). Although map has a concrete implementation of is_surjective, which is a technical detail that would need to be worked around (which that method probably should be lifted to the category of set morphisms).
The fix LGTM.
New commits:
| 79fd62a | ZZ is not onto QQ
|
comment:6 Changed 5 years ago by
| Branch: | u/saraedum/zz___qq_is_not_onto → 79fd62a8c40632891cf32502a3d80709edc68cf8 |
|---|---|
| Resolution: | → fixed |
| Status: | positive_review → closed |
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You should never, ever give information about specific objects at the category level.
However, you can impart this information in the
Z_to_Qmorphism class.