#15612: We need unordered trees
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       Reporter:  darij          |        Owner:
           Type:  task           |       Status:  new
       Priority:  major          |    Milestone:  sage-6.1
      Component:  combinatorics  |   Resolution:
       Keywords:  trees          |    Merged in:
        Authors:                 |    Reviewers:
Report Upstream:  N/A            |  Work issues:
         Branch:                 |       Commit:
   Dependencies:                 |     Stopgaps:
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Description changed by darij:

Old description:

> Of course, the actual implementation will have to wait for #14498 being
> reviewed (hint, hint), but I guess it won't hurt to bring up the matter
> now.
>
> I'd really like to see unordered (=non-planar) trees of various varieties
> (binary/arbitrary, labelled/unlabelled) being implemented in Sage.
> ("Unordered" means that the children of a vertex form a multiset, not a
> list.) I'm wondering if it is possible to implement the labelled kind as
> a finite set with a Maybe-endomorphism (i. e., a partial map from the set
> to itself) while still satisfying the AbstractLabelledTree
> implementation, because I guess this will be a lot faster than following
> the recursive paradigm we currently have.

New description:

 Of course, the actual implementation will have to wait for #14498 being
 reviewed (hint, hint), but I guess it won't hurt to bring up the matter
 now.

 I'd really like to see unordered (=non-planar) trees of various varieties
 (binary/arbitrary, labelled/unlabelled) being implemented in Sage.
 ("Unordered" means that the children of a vertex form a multiset, not a
 list.) I'm wondering if it is possible to implement the labelled kind as a
 finite set with a Maybe-endomorphism (i. e., a partial map from the set to
 itself) while still satisfying the AbstractLabelledTree interface, because
 I guess this will be a lot faster than following the recursive paradigm we
 currently have.

--

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Ticket URL: <http://trac.sagemath.org/ticket/15612#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica, 
and MATLAB

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