#16247: Abuse of Modules() for modules over noncommutative rings
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Reporter: darij | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.2
Component: algebra | Keywords: modules, categories,
Merged in: | associativity,
Reviewers: | Authors:
Work issues: | Report Upstream: N/A
Commit: | Branch:
Stopgaps: | Dependencies:
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We have `LeftModules` and `RightModules` functorial constructions (not
sure if since #10963 or already before), and they should be used.
`Modules` implements left and right multiplication to be *the same*, which
causes misleading and counterintuitive non-associativity issues.
I'm currently running the (short) doctests of src/sage with a commit that
adds a warning every time Modules(A) is called for A noncommutative. I'll
post the results once it's done. So far:
{{{
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sage -t src/sage/groups/finitely_presented.py # 2 doctests failed
sage -t src/sage/matrix/matrix_sparse.pyx # 4 doctests failed
sage -t src/sage/matrix/matrix0.pyx # 5 doctests failed
sage -t src/sage/matrix/matrix2.pyx # 1 doctest failed
sage -t src/sage/matrix/matrix_space.py # 2 doctests failed
Doctests interrupted: 231/2069 files tested
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}}}
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Ticket URL: <http://trac.sagemath.org/ticket/16247>
Sage <http://www.sagemath.org>
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