#14901: Lie algebras
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       Reporter:  tscrim                       |        Owner:  sage-
           Type:  enhancement                  |  combinat
       Priority:  major                        |       Status:  new
      Component:  algebra                      |    Milestone:  sage-5.13
       Keywords:  Lie algebras Kac Moody       |   Resolution:
        Authors:  Travis Scrimshaw             |    Merged in:
Report Upstream:  N/A                          |    Reviewers:
         Branch:                               |  Work issues:
   Dependencies:  #10963 #14898 #15151 #15289  |       Commit:
                                               |     Stopgaps:
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Comment (by tscrim):

 Okay, here's the current version of the patch for reference for those
 don't want to get/use the combinat queue. It does about 80% or so of the
 functionality I want, but it probably could use some restructuring. It's
 also missing a lot of documentation (most importantly doctests). Here's
 what's done and (mostly) working:

 - Free Lie algebras in the Hall basis
 - The Lyndon basis for the free Lie algebra
 - Abelian Lie algebras
 - Lie algebras from an associative algebra
 - Lie algebras from structure coefficients
 - Finite type Lie algebras
   - As matrices for types ABCD
   - In the Chevalley basis
 - '''gl''',,n,,
 - The Lie algebra of strictly upper triangular matrices
 - The Lie algebra of upper triangular matrices
 - Untwisted affine Lie algebras constructed from a finite type
 - Untwisted affine Kac-Moody Lie algebras (i.e. the above and the Lie
 derivative) [done]
 - Universal enveloping algebras
 - Kac-Moody algebras based only on a (generalized) Cartan matrix
 - LLT basis and Fock spaces for U,,q,,('''sl''',,n,,) [done]
 - PBW(-type) bases of universal enveloping algebra (quantum group) [done
 for Lie algebras up to abstracting internal structure]
 - canonical bases of quantum groups [90% done]
 - the Heisenberg Lie algebras and some other misc examples
 - quotient, sub, and direct sum Lie algebras and Lie algebra ideals

 Everything else:

 - twisted affine Lie and Kac-Moody algebras via loop groups/diagram
 automorphims [I want to do this, but haven't started and might push to a
 later ticket]
 - the Goodman and Wenzl modified LLT algorithm [haven't started yet]
 - polynomial representations for '''sl''',,n,, [doesn't give the correct
 results]
 - implementation of quantum groups [65% done]
 - connection between the quantum group and the Hall algebra (coming from
 representations of a quiver over F,,q,,) [I would need to understand Hall
 algebras better to do this]
 - '''su''',,n,, [possibly to be dropped as the Sage infrastructure does
 not seem to be there]
 - recovery of Lie group from Lie algebra (where it makes sense) [0% done,
 likely to be dropped]

--
Ticket URL: <http://trac.sagemath.org/ticket/14901#comment:9>
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