#14541: Family over enumerated set has wrong category
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Reporter: cnassau | Owner:
nthiery
Type: defect | Status:
new
Priority: minor | Milestone:
sage-5.10
Component: categories | Resolution:
Keywords: Family, Category of finite enumerated sets | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by nthiery):
Thanks for the report!
Hmm, that's annoying indeed. This stems from the fact that
{{{Permutations}}} still uses the old CombinatorialClass, and for those
it's not so easy to detect easily whether they are known to be finite.
As a workaround, line 832 of Family, when the input is a
CombinatorialClass, we could ask whether x.cardinality() != infinity. The
risk is to trigger the enumeration of the elements of the combinatorial
class which might take a while ... Or check if cardinality actually is
implemented (i.e. is not the default _cardinality_from_iterator), and if
yes call it.
Of course, the proper fix would be to revamp permutations to be an
enumerated set like has been done recently for tableaux.
Would you be willing to handle any of the above?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14541#comment:1>
Sage <http://www.sagemath.org>
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