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Packages ยป LieTypes :: LieAlgebraModule @ LieAlgebraModule
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LieAlgebraModule @ LieAlgebraModule -- Take the tensor product of modules over different Lie algebras

Synopsis

Description

Produces a module over the direct sum of the Lie algebras of the two modules.

i1 : LL_(1,2,3,4) (simpleLieAlgebra("D",4)) @ LL_(5,6) (simpleLieAlgebra("G",2))

o1 = LL           (๐”ก  ++ ๐”ค )
       1,2,3,4,5,6  4     2

o1 : irreducible LieAlgebraModule over ๐”ก  ++ ๐”ค
                                        4     2

A complicated way to define usual tensor product LieAlgebraModule ** LieAlgebraModule would be using the diagonal embedding:

i2 : g := simpleLieAlgebra("A",1)

o2 = ๐”ž
      1

o2 : simple LieAlgebra
i3 : h := g ++ g

o3 = ๐”ž  ++ ๐”ž
      1     1

o3 : LieAlgebra
i4 : gdiag := subLieAlgebra(h,matrix {{1},{1}})

o4 = ๐”ž
      1

o4 : simple LieAlgebra, subalgebra of ๐”ž  ++ ๐”ž
                                       1     1
i5 : M = LL_5 (g); M' = LL_2 (g);
i7 : M @ M'

o7 = LL   (๐”ž  ++ ๐”ž )
       5,2  1     1

o7 : irreducible LieAlgebraModule over ๐”ž  ++ ๐”ž
                                        1     1
i8 : branchingRule(oo,gdiag)

o8 = LL (๐”ž ) ++ LL (๐”ž ) ++ LL (๐”ž )
       3  1       5  1       7  1

o8 : LieAlgebraModule over ๐”ž
                            1
i9 : M ** M'

o9 = LL (๐”ž ) ++ LL (๐”ž ) ++ LL (๐”ž )
       3  1       5  1       7  1

o9 : LieAlgebraModule over ๐”ž
                            1

Ways to use this method: