#17979: Reimplementation of IntegerListsLex
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Reporter: aschilling | Owner:
Type: defect | Status: needs_work
Priority: blocker | Milestone: sage-6.6
Component: combinatorics | Resolution:
Keywords: days64 | Merged in:
Authors: Bryan Gillespie, | Reviewers:
Anne Schilling, Nicolas M. Thiery | Work issues: support n in an
Report Upstream: N/A | iterable
Branch: | Commit:
public/ticket/17979 | 6153cf8d39dc23cb41a3d0c2ea66ba5dc3abd2c0
Dependencies: | Stopgaps:
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Comment (by jdemeyer):
Replying to [comment:27 ncohen]:
> - It seems that currently the method accepts input that does not satisfy
the
> constraints that you list, i.e.:
>
> {{{
> sage: IntegerListsLex(min_n=4)
> Integer lists of sum between 4 and 0 satisfying certain constraints
> sage: list(IntegerListsLex(min_n=4))
> []
> }}}
>
> Should they really be considered as 'constraints', if the code accepts
them
> and returns sensible output (i.e. empty sets)?
I think that returning the empty set is the right answer here. As long as
the question makes sense ''mathematically'', there should be an answer,
not an exception.
The only thing which can be a `ValueError` exception would be a negative
length, since that doesn't even have a mathematical meaning. But I know
from #17920 that some `Partitions` code gives a negative minimum length,
so a negative value for `min_length` should just be treated as 0.
--
Ticket URL: <http://trac.sagemath.org/ticket/17979#comment:54>
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