#8881: Functorial constructions in categories
---------------------------------+------------------------------------------
Reporter: hivert | Owner: nthiery
Type: enhancement | Status: needs_review
Priority: critical | Milestone: sage-4.4.3
Component: categories | Keywords: Functorial constructions
Author: Nicolas M. Thiéry | Upstream: N/A
Reviewer: Florent Hivert | Merged:
Work_issues: |
---------------------------------+------------------------------------------
Changes (by hivert):
* status: needs_work => needs_review
Old description:
> This patch refactors completely the framework for (covariant)
> functorial constructions, improves the existing ones, and adds new ones.
>
> Improved constructions:
> - Cartesian products: generalization to non modules_with_basis,
> monoid operations, ...
>
> New constructions:
> - Subquotients, Quotients, Subobjects, IsomorphicObjects
> - DualObjects, Algebras
>
> Miscellaneous category fixes and improvements:
> - is_subcategory now handles properly join categories
> (courtesy of Florent Hivert)
> - For a field K, Modules(K) returns VectorSpaces(K)
> - As a temporary workaround, Parent._an_element_ calls the
> _an_element_ method provided by the categories, if available
> - Adds a method Category.or_subcategory
> - Cleans up _repr_ by extracting a _repr_object_names method
> - Cleans up _latex_ by extracting a _short_name method
New description:
This patch refactors completely the framework for (covariant)
functorial constructions, improves the existing ones, and adds new ones.
Improved constructions:
- Cartesian products: generalization to non modules_with_basis,
monoid operations, ...
New constructions:
- Subquotients, Quotients, Subobjects, IsomorphicObjects
- DualObjects, Algebras
Miscellaneous category fixes and improvements:
- is_subcategory now handles properly join categories
(courtesy of Florent Hivert)
- For a field K, Modules(K) returns VectorSpaces(K)
- As a temporary workaround, Parent._an_element_ calls the
_an_element_ method provided by the categories, if available
- Adds a method Category.or_subcategory
- Cleans up _repr_ by extracting a _repr_object_names method
- Cleans up _latex_ by extracting a _short_name method
Depend on #9104
--
Comment:
Replying to [comment:7 was]:
> This causes doctest failures, including the following.
{{{
>
> sage -t sage/categories/sets_cat.py
> **********************************************************************
> File
"/mnt/usb1/scratch/wstein/build/release/4.4.3/sage-4.4.3.alpha2/devel
/sage-main/sage/categories/sets_cat.py", line 624:
> sage: A = Monoids().example().algebra(QQ); A
> Exception raised:
. [...]
> AttributeError: 'CombinatorialFreeModule_with_category' object has
no attribute '_name'
> **********************************************************************
> File
"/mnt/usb1/scratch/wstein/build/release/4.4.3/sage-4.4.3.alpha2/devel
/sage-main/sage/categories/sets_cat.py", line 626:
> sage: A.category()
> Expected:
> Category of monoid algebras over Rational Field
> Got:
> Category of set algebras over Rational Field
> **********************************************************************
}}}
This bug is fixed in #9104 but it does appear on 4.4.2 so I didn't think
about a dependency. Sorry for this.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8881#comment:8>
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