Opened 3 years ago

Closed 3 years ago

Last modified 3 years ago

#23660 closed enhancement (fixed)

Better isomorphisms between function fields and fraction fields

Reported by: saraedum Owned by:
Priority: minor Milestone: sage-8.1
Component: commutative algebra Keywords: function field, fraction field
Cc: Merged in:
Authors: Julian Rüth Reviewers: Jean-Pierre Flori
Report Upstream: N/A Work issues:
Branch: 746eac0 (Commits) Commit:
Dependencies: Stopgaps:

Description

Add a method function_field to fraction fields of univariate polynomial rings over fields which returns the isomorphic function field. Also, the involved morphisms should know that they are injective and surjective.

Change History (14)

comment:1 Changed 3 years ago by saraedum

  • Branch set to u/saraedum/better_isomorphisms_between_function_fields_and_fraction_fields

comment:2 Changed 3 years ago by saraedum

  • Commit set to f6dd0cd739bce6cd1d5016c38ce45f712d84b455
  • Status changed from new to needs_review

New commits:

f6dd0cdBetter isomorphisms between fraction fields and function fields

comment:3 Changed 3 years ago by jpflori

  • Reviewers set to Jean-Pierre Flori

Looks fine.

Maybe you could make the paragraph in _richcmp_ a warning or note block.

comment:4 Changed 3 years ago by saraedum

done.

comment:5 Changed 3 years ago by git

  • Commit changed from f6dd0cd739bce6cd1d5016c38ce45f712d84b455 to 38f18b8aafcca641cd8ab4f2a3c5786f90a75703

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

38f18b8minor docstring change

comment:6 Changed 3 years ago by jpflori

  • Status changed from needs_review to positive_review

comment:7 Changed 3 years ago by vbraun

  • Status changed from positive_review to needs_work
File "src/sage/categories/rings.py", line 117, in sage.categories.rings.Rings.MorphismMethods.is_injective
Failed example:
    f = ZZ.hom(K); f
Expected:
    Composite map:
      From: Integer Ring
      To:   Rational function field in x over Rational Field
      Defn:   Conversion via FractionFieldElement_1poly_field map:
              From: Integer Ring
              To:   Fraction Field of Univariate Polynomial Ring in x over Rational Field
            then
              Coercion map:
              From: Fraction Field of Univariate Polynomial Ring in x over Rational Field
              To:   Rational function field in x over Rational Field
Got:
    Composite map:
      From: Integer Ring
      To:   Rational function field in x over Rational Field
      Defn:   Conversion via FractionFieldElement_1poly_field map:
              From: Integer Ring
              To:   Fraction Field of Univariate Polynomial Ring in x over Rational Field
            then
              Isomorphism morphism:
              From: Fraction Field of Univariate Polynomial Ring in x over Rational Field
              To:   Rational function field in x over Rational Field

comment:8 Changed 3 years ago by git

  • Commit changed from 38f18b8aafcca641cd8ab4f2a3c5786f90a75703 to 8bfe3264d4a00436a48c761f924a8620c33f476f

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

8bfe326Merge branch 'develop' into t/23660/better_isomorphisms_between_function_fields_and_fraction_fields

comment:9 Changed 3 years ago by git

  • Commit changed from 8bfe3264d4a00436a48c761f924a8620c33f476f to 746eac0e4207510956254935f2aa8d3e602b72b7

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

746eac0fix docstring

comment:10 Changed 3 years ago by saraedum

  • Status changed from needs_work to needs_review
  • Work issues set to patchbot happy⇒back to positive review

comment:11 Changed 3 years ago by roed

  • Status changed from needs_review to positive_review
  • Work issues patchbot happy⇒back to positive review deleted

Patchbot's happy.

comment:12 Changed 3 years ago by vbraun

  • Branch changed from u/saraedum/better_isomorphisms_between_function_fields_and_fraction_fields to 746eac0e4207510956254935f2aa8d3e602b72b7
  • Resolution set to fixed
  • Status changed from positive_review to closed

comment:13 Changed 3 years ago by jdemeyer

  • Commit 746eac0e4207510956254935f2aa8d3e602b72b7 deleted

This broke #23881 :-(

comment:14 Changed 3 years ago by jdemeyer

Follow-up: #24033

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