#12630: Add representations of quivers and quiver algebras to sage
-------------------------------------+-------------------------------------
       Reporter:  JStarx             |        Owner:  AlexGhitza
           Type:  enhancement        |       Status:  needs_review
       Priority:  major              |    Milestone:  sage-6.2
      Component:  algebra            |   Resolution:
       Keywords:  algebra, quiver,   |    Merged in:
  module, days49                     |    Reviewers:  Simon King
        Authors:  Jim Stark, Simon   |  Work issues:
  King, Mathieu Guay-Paquet, Aladin  |       Commit:
  Virmaux                            |  48a8fed2d0503ea4bf4312c9a942c1fd024b0917
Report Upstream:  N/A                |     Stopgaps:
         Branch:                     |
  public/combinat/quivers            |
   Dependencies:  #12412, #12413,    |
  #14806, #15491, #15623, #15810     |
-------------------------------------+-------------------------------------

Comment (by nthiery):

 Replying to [comment:245 SimonKing]:
 > Replying to [comment:244 nthiery]:
 > > - Maybe  {{{QuiverRepElement}}} could inherit from
 {{{ElementWrapper}}}? That would give it e.g. the hash for free.
 >
 > No idea about this. I don't know how it works.

 It's really just a simple base class that handle the trivial stuff
 when one wants to implement an element whose data structure consists
 of a single object (e.g. a tuple). See ElementWrapper?

 > We are talking about `QuiverRepElement`, right? Well, eventually this
 should become faster, too (but first, I'll focus on paths). After all, I
 plan to implement an F5 algorithm for modules over path algebras, and
 speed will be absolutely critical. But this could actually require more
 trickery (even free-lists, to save the time that is vasted for creating
 and deleting elements)---so much that it could be that internally I will
 use classes that will not be exposed to the user. So, perhaps internally I
 will use a class (certainly Cython cdef class) that has almost nothing to
 do with the current implementation.

 Oh I see; I mistakenly thought it was modeling an element representing
 a quiver representation. Not an element thereof. Now I see the
 potential need for speed.

 > > - is there a reason to use {{{UniqueFactory}}} rather than
 {{{UniqueRepresentation}}}?
 >
 > We have long code to create a cache key, and we have long code to create
 an object from a given key (which involves choosing among different
 implementations). I think `UniqueFactory` is a better tool, since (in
 contrast to `UniqueRepresentation`) it allows for a clean separation
 between the two requirements "create key" and "create object".

 Ok. At some point we should think about whether we could make a better
 distinction in UniqueRepresentation. But that's of course for later.

 Cheers,
                                    Nicolas

--
Ticket URL: <http://trac.sagemath.org/ticket/12630#comment:249>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica, 
and MATLAB

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