Opened 5 years ago

Closed 5 years ago

## #23495 closed enhancement (fixed)

# R[x]→S[x] is injective/surjective if R→S is

Reported by: | Julian Rüth | Owned by: | |
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Priority: | minor | Milestone: | sage-8.1 |

Component: | commutative algebra | Keywords: | sd87, beginner |

Cc: | Merged in: | ||

Authors: | Julian Rüth | Reviewers: | Adele Bourgeois |

Report Upstream: | N/A | Work issues: | |

Branch: | 18169e4 (Commits, GitHub, GitLab) | Commit: | 18169e4708fe8a62e6f60785db16eabd5a4e9bb2 |

Dependencies: | #23483, #23204 | Stopgaps: |

### Description

sage: R.<x> = ZZ[] sage: S.<x> = QQ[] sage: R.hom(S).is_injective() NotImplementedError

### Change History (12)

### comment:1 Changed 5 years ago by

Branch: | → u/saraedum/r_x__s_x__is_injective_surjective_if_r_s_is |
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### comment:2 Changed 5 years ago by

Commit: | → 18169e4708fe8a62e6f60785db16eabd5a4e9bb2 |
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Dependencies: | → #23483 |

### comment:3 Changed 5 years ago by

Status: | new → needs_review |
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### comment:4 Changed 5 years ago by

Status: | needs_review → needs_work |
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### comment:5 Changed 5 years ago by

Dependencies: | #23483 → #23483, #23204 |
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### comment:6 Changed 5 years ago by

Status: | needs_work → needs_review |
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### comment:7 Changed 5 years ago by

All doctests pass on src/sage/rings/polynomial/polynomial_ring_homomorphism.pyx. When testing doctests on src/sage/rings, I get the following output at the end:

---------------------------------------------------------------------- sage -t --warn-long 37.9 src/sage/rings/finite_rings/finite_field_prime_modn.py # 2 doctests failed sage -t --warn-long 37.9 src/sage/rings/morphism.pyx # 2 doctests failed ----------------------------------------------------------------------

I think that maybe the failures in morphism.pyx are related to #23485. However, I am not sure about finite_field_prime_modn.py.

### comment:8 Changed 5 years ago by

Reviewers: | → Adele Bourgeois |
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### comment:9 Changed 5 years ago by

Thanks for reporting these. The `morphism.pyx`

is fixed now. The other one comes from #23204. I am fixing it there.

### comment:12 Changed 5 years ago by

Branch: | u/saraedum/r_x__s_x__is_injective_surjective_if_r_s_is → 18169e4708fe8a62e6f60785db16eabd5a4e9bb2 |
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Resolution: | → fixed |

Status: | positive_review → closed |

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New commits:

`R[x]→S[x] is injective/surjective iff R→S is`