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LieTypes minor update
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pzinn authored and mikestillman committed Sep 16, 2023
1 parent 1efc269 commit ef5b185
Showing 1 changed file with 32 additions and 15 deletions.
47 changes: 32 additions & 15 deletions M2/Macaulay2/packages/LieTypes.m2
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@
-- licensed under GPL v2 or any later version
newPackage(
"LieTypes",
Version => "0.8",
Version => "0.81",
Date => "Jan 22, 2023",
Headline => "common types and methods for Lie groups and Lie algebras",
Authors => {
Expand Down Expand Up @@ -51,7 +51,7 @@ export {
"subLieAlgebra",
--for the LieAlgebraModule type
"LieAlgebraModule",
"irreducibleLieAlgebraModule", "LL",
"irreducibleLieAlgebraModule", "LL", "ω",
-- "isIsomorphic",
"casimirScalar",
"weightDiagram",
Expand Down Expand Up @@ -402,7 +402,7 @@ LieAlgebra#AfterPrint = g -> (
LieAlgebraModule = new Type of HashTable
LieAlgebraModule.GlobalAssignHook = globalAssignFunction
LieAlgebraModule.GlobalReleaseHook = globalReleaseFunction
LL = new ScriptedFunctor from { subscript => w -> g -> irreducibleLieAlgebraModule(try toList w else {w},g) }
LL = new ScriptedFunctor from { subscript => w -> g -> irreducibleLieAlgebraModule(g,w) }
LL.texMath = ///{\mathcal L}///

describe LieAlgebraModule := M -> Describe (
Expand Down Expand Up @@ -512,16 +512,24 @@ LieAlgebraModule.directSum = args -> (
)
LieAlgebraModule ++ LieAlgebraModule := directSum

ωsub := i -> Subscript{symbol ω,i};
ω=new ScriptedFunctor from { subscript => ωsub }
irreducibleLieAlgebraModule = method(
TypicalValue => LieAlgebraModule
)
irreducibleLieAlgebraModule(List,LieAlgebra) := (v,g) -> (
irreducibleLieAlgebraModule(LieAlgebra,List) := (g,v) -> (
v = deepSplice v;
if #v != rank g or not all(v, a -> class a === ZZ) then error "wrong highest weight";
if #v != rank g or not all(v, a -> class a === ZZ) then error "invalid highest weight";
new LieAlgebraModule from (g,{v => 1})
)
irreducibleLieAlgebraModule(Vector,LieAlgebra) := (v,g) -> irreducibleLieAlgebraModule(entries v,g)
irreducibleLieAlgebraModule(LieAlgebra,List) := irreducibleLieAlgebraModule(LieAlgebra,Vector) := (g,v) -> irreducibleLieAlgebraModule(v,g)
irreducibleLieAlgebraModule(LieAlgebra,VisibleList) := (g,v) -> irreducibleLieAlgebraModule(g,toList v)
irreducibleLieAlgebraModule(LieAlgebra,Vector) := (g,v) -> irreducibleLieAlgebraModule(g,entries v)
irreducibleLieAlgebraModule(LieAlgebra,ZZ) := (g,v) -> irreducibleLieAlgebraModule(g,{v})
irreducibleLieAlgebraModule(LieAlgebra,Expression) := (g,v) -> (
ω.subscript = i -> apply(rank g,j->if j+1==i then 1 else 0 );
irreducibleLieAlgebraModule(g,first(value v,ω.subscriptsub))
)
irreducibleLieAlgebraModule(Thing,LieAlgebra) := (v,g) -> irreducibleLieAlgebraModule(g,v)

-*-----------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------
Expand Down Expand Up @@ -1437,8 +1445,11 @@ doc ///
the simple Lie algebra with the given rank and type
Description
Text
The classification of simple Lie algebras over the complex numbers is well known. There are four infinite families (types A, B, C, D) corresponding to the Lie algebras $sl(n+1,\mathbb{C})$, $so(2n+1,\mathbb{C})$, $sp(2n,\mathbb{C})$, $so(2n,\mathbb{C})$ respectively, and five exceptional simple Lie algebras, E6, E7, E8, F4, G2.

The classification of simple Lie algebras over the complex numbers is well known.
There are four infinite families (types $\mathfrak{a}_n$, $\mathfrak{b}_n$, $\mathfrak{c}_n$, $\mathfrak{d}_n$) corresponding to the Lie algebras
$\mathfrak{sl}(n+1,\mathbb{C})$, $\mathfrak{so}(2n+1,\mathbb{C})$, $\mathfrak{sp}(2n,\mathbb{C})$, $\mathfrak{so}(2n,\mathbb{C})$ respectively,
and five exceptional simple Lie algebras, $\mathfrak{e}_6$, $\mathfrak{e}_7$, $\mathfrak{e}_8$, $\mathfrak{f}_4$, $\mathfrak{g}_2$.

Example
--simpleLieAlgebra(sl_2)
simpleLieAlgebra("A",1)
Expand Down Expand Up @@ -1695,23 +1706,26 @@ doc ///
class for Lie algebra modules
Description
Text
This class represents Lie algebra modules. Currently only modules over simple Lie algebras over the complex numbers are supported. An object of type LieAlgebraModule is a hash table recording the Lie algebra and the decomposition of the module into irreducible Lie algebra modules, which are indexed by their highest weights.
This class represents Lie algebra modules. Currently only modules over semi-simple Lie algebras over the complex numbers are supported.
An object of type LieAlgebraModule is a hash table recording the Lie algebra and the decomposition of the module into irreducible Lie algebra modules, which are indexed by their highest weights.

Example
g=simpleLieAlgebra("A",2)
M=irreducibleLieAlgebraModule({1,1},g)
M=irreducibleLieAlgebraModule(g,{1,1})
///

doc ///
Key
irreducibleLieAlgebraModule
(irreducibleLieAlgebraModule,List,LieAlgebra)
(irreducibleLieAlgebraModule,Vector,LieAlgebra)
(irreducibleLieAlgebraModule,LieAlgebra,List)
(irreducibleLieAlgebraModule,LieAlgebra,Vector)
LL
ω
Headline
construct the irreducible Lie algebra module with given highest weight
Usage
irreducibleLieAlgebraModule(w,g)
irreducibleLieAlgebraModule(g,w)
Inputs
w:List
the highest weight of the desired module
Expand All @@ -1723,11 +1737,14 @@ doc ///
This function creates the irreducible Lie algebra module with a given highest weight.
Example
g=simpleLieAlgebra("A",2)
irreducibleLieAlgebraModule({1,1},g)
irreducibleLieAlgebraModule(g,{1,1})
Text
One can also use the shorthand LL:
Example
LL_(1,1) (g)
Text
as well as the shorthand ω:
LL_(ω_2) (g)
///

TEST ///
Expand Down Expand Up @@ -2459,7 +2476,7 @@ undocumented ( {
(symbol ==,LieAlgebraModule,LieAlgebraModule), (symbol ==,LieAlgebraModule,ZZ),
(NewFromMethod,LieAlgebraModule,Sequence),
(symbol ^,LieAlgebraModule,QQ),
(irreducibleLieAlgebraModule,LieAlgebra,Vector), (irreducibleLieAlgebraModule,LieAlgebra,List),
(irreducibleLieAlgebraModule,LieAlgebra,ZZ), (irreducibleLieAlgebraModule,LieAlgebra,VisibleList), (irreducibleLieAlgebraModule,LieAlgebra,Expression), (irreducibleLieAlgebraModule,Thing,LieAlgebra),
(dynkinDiagram,String,ZZ),(cartanMatrix,String,ZZ),(cartanMatrix,Sequence,Sequence),(isSimple,String,ZZ),isSimple,(isSimple,LieAlgebra),
(dim,LieAlgebra),(rank,LieAlgebra),
(character,String,ZZ,List),(character,Sequence,Sequence,List),
Expand Down

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