#14775: Symmetric functions: extending Kronecker product, implementing Kronecker
product, extending antipode, extending forgotten basis, implementing Witt
basis
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       Reporter:  darij                                                    |    
     Owner:  sage-combinat
           Type:  enhancement                                              |    
    Status:  new          
       Priority:  major                                                    |    
 Milestone:  sage-5.11    
      Component:  combinatorics                                            |    
Resolution:               
       Keywords:  symmetric function, combinat, kronecker product, days49  |   
Work issues:               
Report Upstream:  N/A                                                      |    
 Reviewers:               
        Authors:  Darij Grinberg                                           |    
 Merged in:               
   Dependencies:                                                           |    
  Stopgaps:               
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Comment (by darij):

 While there are good formulas for the h, e, p bases in terms of the w
 bases, as well as not-too-slow algorithms for the w basis in terms of the
 h, e, p bases (basically by inverting the formulas just mentioned), I am
 not sure which of them I should implement. Right now I have implemented
 h-to-w and w-to-h, declaring them as coercions, and p-to-w. The h-to-w and
 w-to-h coercions use a cache like the ones in {{{dual.py}}}. Now I need
 guidance on the following:

 1) Is it a good idea to also use cache for e-to-w and w-to-e? (The
 downside is that there will be more caches in memory.) Same for p-to-w (my
 current implementation is cacheless, thus not as fast as it could be) and
 w-to-p.

 2) If I implement these maps, should I register them as coersions? (This
 would normally make sense, but I fear they could significantly slow down
 coercions between standard classical bases because of the asinine way the
 current system generates coercion paths.)

-- 
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14775#comment:9>
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