#14751: Regression in representation of CombinatorialFreeModules (introduced
#13735)
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Reporter: agd | Owner: agd
Type: defect | Status: new
Priority: major | Milestone: sage-5.11
Component: misc | Keywords:
Work issues: | Report Upstream: N/A
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
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The patch applied by ticket #13735 changes the behavior of the
repr_lincomb method in misc/misc.py so that it now evaluates the
comparison "c < 0" for every coefficient. However, since this method is
called by CombinatorialFreeModule, which can create lienar combinations
whose coefficients are elements of arbitrary rings, this comparison is not
always mathematically meaningful.
For example, in the code I submitted in #14347, I build a
CombinatorialFreeModule whose basis is a specified finite group G and
whose coefficients are elements of a CycleIndexSeriesRing. In 5.9, this
was perfectly functional; in 5.10-rc2, with the new patch, any call to
_repr_ on an element of this CombinatorialFreeModule results in a
NotImplementedError because of this comparison.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14751>
Sage <http://www.sagemath.org>
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