#5457: Refactor symmetric functions and k-bounded subspace
---------------------------------------------------+------------------------
       Reporter:  nthiery                          |         Owner:  mhansen    
             
           Type:  enhancement                      |        Status:  new        
             
       Priority:  major                            |     Milestone:  sage-5.3   
             
      Component:  combinatorics                    |    Resolution:             
             
       Keywords:  symmetric functions, sd38, sd40  |   Work issues:             
             
Report Upstream:  N/A                              |     Reviewers:  Dan Bump, 
Franco Saliola
        Authors:  Mike Zabrocki, Anne Schilling    |     Merged in:             
             
   Dependencies:                                   |      Stopgaps:             
             
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Changes (by {'newvalue': u'Mike Zabrocki, Anne Schilling', 'oldvalue': ''}):

  * keywords:  => symmetric functions, sd38, sd40
  * reviewer:  => Dan Bump, Franco Saliola
  * author:  => Mike Zabrocki, Anne Schilling


Old description:

> Refactor symmetric functions to:
>  - use a single entry point, as in MuPAD-Combinat. Something like:
>       -  S = SymmetricFunctions(field)
>       -  S.schur
>       -  S.jack(t).P
>       -  S.macdonald(t,q).Q
>       -  S.kSchur(3).H
>  - use the coercion framework
>  - use the category framework
>
> See also:http://groups.google.com/group/sage-devel/msg/a49f3288fca1b75c

New description:

 This patch restructures the implementation of symmetric functions in sage

 The new implementation makes use of multiple realizations and the category
 framework. The new access to symmetric functions is via
 {{{
 sage: Sym = SymmetricFunctions(QQ)
 }}}

 Further new features that are implemented:

 - The ring of symmetric functions is now endowed with a Hopf algebra
 structure.
   The coproduct and antipode are implemented (which were missing before).

 - A tutorial on how to use symmetric functions in sage is included at the
   beginning of sf.py which is also accessible via
 {{{
 sage: SymmetricFunctions??
 }}}

 - Symmetric functions should now work a lot better with respect to
   specializing parameters like `q` and `t` for Hall-Littlewood, Jack
   and Macdonald symmetric functions. Certain functionalities before
   this change were broken or not possible.

 - Documentation was added to LLT polynomials (which had very sparse
 documentation
   previously).

 - The `k`-bounded subspace of the ring of symmetric function was
 implemented.
   The `k`-Schur functions now live in the `k`-bounded subspace rather than
   in the ring of symmetric functions as before.

 This patch gained tremendously by the tutorial on symmetric functions
 written
 by Jason Bandlow and Nicolas Thiery, a draft on the `k`-bounded subspace
 by
 Jason Bandlow, and code multiple realizations written by Franco Saliola.

 See also:http://groups.google.com/group/sage-devel/msg/a49f3288fca1b75c

--

-- 
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5457#comment:5>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica, 
and MATLAB

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