#17979: Reimplementation of IntegerListsLex
-------------------------------------+-------------------------------------
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: Nathann Cohen, Jeroen
Anne Schilling, Nicolas M. Thiery | Demeyer, Travis Scrimshaw
Report Upstream: N/A | Work issues:
Branch: | Commit:
public/ticket/17979 | d6ead16b70d759dcc084bac3481e9d4f88121146
Dependencies: | Stopgaps:
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Comment (by aschilling):
Replying to [comment:429 ncohen]:
> > > - Are `min_sum` and `max_sum` also ignored when `n` is a list? From
the doc it
> > > seems to be, though I am not sure that it is the best design choice
in this
> > > case.
> > >
> >
> > Yes. As far as I know this is how it was before.
> >
>
> What do you think of it?
As stated in the documentation, this feature is kept for backward
compatibility, see
{{{
sage: from sage.combinat.integer_list_old import IntegerListsLex as
IntegerListsLexOld
sage: IntegerListsLexOld([2,2],length=2).list()
/Applications/sage/src/bin/sage-ipython:1:
********************************************************************************
The old implementation of IntegerListsLex does not allow for arbitrary
input; non-allowed input can return wrong results, please see the
documentation for IntegerListsLex for details.
This issue is being tracked at
http://trac.sagemath.org/sage_trac/ticket/17548.
********************************************************************************
[[2, 0], [1, 1], [0, 2], [2, 0], [1, 1], [0, 2]]
}}}
> > > - In the following text which says that one can force the
enumeration when it is
> > > formally impossible, can you explicitly say what will happen? "All
possible
> > > lists are enumerated, but the ordering is incorrect" or something?
> > > `If one wants to proceed anyway, one can sign a waiver by setting
check=False:`
> > >
> >
> > When a function for the floor or ceiling is given, it is impossible to
check that
> > the conditions give a finite set since the list of values is in
principle infinite.
> > In this case the algorithm can either hang (as it computes more and
more parts of the
> > integer list) or it can happen that a tail of 000100000.... will
appear in which case
> > nor all elements in the list will be iterated over.
> >
>
> Can you make this explicit in the doc?
It is. See line 403 onward.
> > See the documentation!
> >
>
> It does not address the problem that output is not sorted as it should.
It is documented what it does and that it does not sort it the way you
suggest.
See line 496 onward.
--
Ticket URL: <http://trac.sagemath.org/ticket/17979#comment:431>
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