#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:
Report Upstream: N/A | Commit:
Branch: | ae225b3af4329dcbedbbfe83151a000b09ef44d3
public/ticket/17979 | Stopgaps:
Dependencies: |
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Comment (by aschilling):
Replying to [comment:155 ncohen]:
> > The reason for this behavior is the following: we identify elements
which differ by trailing zeroes up to max_length. That is why the first
and second example gives True and the last one gives False (since in this
case we are beyond the max_length).
>
> Soooooooooo when you get the list `[2,2,0]` in the output of `.list()`,
it represents "all lists beginning by `2,2,0` whose length is included
between 3 and 4"? This information is not included in the object itself,
it is to be understood by how it was first produced.
The parent knows about the min_length and max_length, so it makes sense to
identify objects with trailing zeroes in the correct parameter range. In
any case, this is the same behavior as in the old version of the code and
I do not think we should change this here.
> This identification of list worries me a bit. The exception in
`__iter__` was added because we consider it a bug that some element of the
set may never be listed in `__iter__`, and this is exactly the problem we
have again here. For a different reason, i.e. because some lists are
identified.
Nathann, this is a different issue! The above issue is just about
identifying objects, not about not listing all of them. The issue about
not listing all of them is due to the fact that inverse lexicographic
order intrinsicly (by definition) does not list them all.
Anne
----
New commits:
||[http://git.sagemath.org/sage.git/commit/?id=ae225b3af4329dcbedbbfe83151a000b09ef44d3
ae225b3]||{{{17979: reverse lexicographic -> inverse lexicographic}}}||
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Ticket URL: <http://trac.sagemath.org/ticket/17979#comment:159>
Sage <http://www.sagemath.org>
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