#11900: Serious regression caused by #9138
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Reporter: SimonKing
| Owner: tbd
Type: defect
| Status: needs_work
Priority: critical
| Milestone: sage-4.8
Component: performance
| Keywords: categories regression
Work_issues: Laurent series rings are fields. Add docs. Don't use is_ring and
friends | Upstream: N/A
Reviewer: Jeroen Demeyer, Nicolas M. Thiéry
| Author: Simon King
Merged:
| Dependencies: #9138 #11911
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Comment(by SimonKing):
Aha! It is an actual bug!
Namely, there are different parent methods called `product` defined in
sage.categories.magmas: For Magmas, for Cartesian products of magmas, and
for subquotients of magmas. Only in the first case is defined
`product_from_element_class_mul = product`. So, if we have a quotient of a
magma, then ALWAYS we will have
`self.product!=self.product_from_element_class_mul`, and thus ALWAYS will
the custom `_mul_` of elements be overridden by the generic stuff.
I'm fixing that, and then I can also have the category framework with a
proper quotient category for polynomial quotient rings.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11900#comment:134>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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