#23660 closed enhancement (fixed)
Better isomorphisms between function fields and fraction fields
Reported by:  saraedum  Owned by:  

Priority:  minor  Milestone:  sage8.1 
Component:  commutative algebra  Keywords:  function field, fraction field 
Cc:  Merged in:  
Authors:  Julian Rüth  Reviewers:  JeanPierre 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
 Branch set to u/saraedum/better_isomorphisms_between_function_fields_and_fraction_fields
comment:2 Changed 3 years ago by
 Commit set to f6dd0cd739bce6cd1d5016c38ce45f712d84b455
 Status changed from new to needs_review
comment:3 Changed 3 years ago by
 Reviewers set to JeanPierre Flori
Looks fine.
Maybe you could make the paragraph in _richcmp_
a warning or note block.
comment:4 Changed 3 years ago by
done.
comment:5 Changed 3 years ago by
 Commit changed from f6dd0cd739bce6cd1d5016c38ce45f712d84b455 to 38f18b8aafcca641cd8ab4f2a3c5786f90a75703
Branch pushed to git repo; I updated commit sha1. New commits:
38f18b8  minor docstring change

comment:6 Changed 3 years ago by
 Status changed from needs_review to positive_review
comment:7 Changed 3 years ago by
 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
 Commit changed from 38f18b8aafcca641cd8ab4f2a3c5786f90a75703 to 8bfe3264d4a00436a48c761f924a8620c33f476f
Branch pushed to git repo; I updated commit sha1. New commits:
8bfe326  Merge branch 'develop' into t/23660/better_isomorphisms_between_function_fields_and_fraction_fields

comment:9 Changed 3 years ago by
 Commit changed from 8bfe3264d4a00436a48c761f924a8620c33f476f to 746eac0e4207510956254935f2aa8d3e602b72b7
Branch pushed to git repo; I updated commit sha1. New commits:
746eac0  fix docstring

comment:10 Changed 3 years ago by
 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
 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
 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
 Commit 746eac0e4207510956254935f2aa8d3e602b72b7 deleted
This broke #23881 :(
comment:14 Changed 3 years ago by
Followup: #24033
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Better isomorphisms between fraction fields and function fields