#14844: Implement cluster algebras with universal coefficients
-------------------------------------+-------------------------------------
       Reporter:  etn40ff            |        Owner:  sage-combinat
           Type:  enhancement        |       Status:  needs_review
       Priority:  minor              |    Milestone:  sage-6.2
      Component:  combinatorics      |   Resolution:
       Keywords:  cluster algebras   |    Merged in:
        Authors:  Salvatore Stella   |    Reviewers:
Report Upstream:  N/A                |  Work issues:
         Branch:                     |       Commit:
  public/ticket/14844                |  5d7bc4df616bc055a9c58906c6030975feea68de
   Dependencies:                     |     Stopgaps:
-------------------------------------+-------------------------------------
Changes (by etn40ff):

 * status:  needs_info => needs_review
 * changetime:  03/05/14 04:32:32 => 03/05/14 04:32:32
 * time:  07/01/13 05:23:10 => 07/01/13 05:23:10


Old description:

> This is a first implementation of cluster algebras with universal
> coefficients.
>
> It is far from being optimal for several reasons. The biggest issues
> comes from an incompatibility between QuiverMutationType and CartanType:
> there is no clean way to translate one into the other. A more subtle
> issue is that CartanType does not allow to choose the ordering on simple
> roots while in a cluster algebra everything is defined up to relabeling.
> To solve these issues, in this patch,  the set of positive roots is
> computed by hand. As a consequence the order in which they appear is not
> the standard one.
>
> For the overall development of sage we might consider a cleanup and
> extension of CartanType, RootSystem etc to allow Cartan matrices as
> input.

New description:

 This is a first implementation of cluster algebras with universal
 coefficients.

 It is far from being optimal for several reasons. The biggest issues comes
 from an incompatibility between QuiverMutationType and CartanType: there
 is no clean way to translate one into the other. A more subtle issue is
 that CartanType does not allow to choose the ordering on simple roots
 while in a cluster algebra everything is defined up to relabeling.
 To solve these issues, in this patch,  the set of positive roots is
 computed by hand. As a consequence the order in which they appear is not
 the standard one.

 For the overall development of sage we might consider a cleanup and
 extension of CartanType, RootSystem etc to allow Cartan matrices as input.

--

--
Ticket URL: <http://trac.sagemath.org/ticket/14844#comment:7>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica, 
and MATLAB

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