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BindGlobal( "LieIsomorphism", function(L1,L2,S,varlist)
local cst, filt, n, F, ser1, ser2, cen1, cen2, dser1,
dser2, H1, cart1, H2, cart2, lev1, lev2, nrad1,
nrad2, HL1, adH1, i, mat, HL2, adH2, A1, A2, R1,
R2, B1, B2, C1, C2, Id1, b, Id2, spaces1, inds,
j, sp, k, sp1, l, sp2, m, sp3, r, sp4, spaces2,
s, bas1, bas2, pp, cont, bb1, bb2, i1, i2, x,
ii1, T1, T2, vars, str, weights, R, indets,
map, d, mats, bass1, M, I, ll1, p, ll2,
o, fl, c, ll3, npar;
npar:= Length( varlist );
cst:=function(T,S,i,j,k,a,b,c,map)
local cij, pos, p, ef, l, mon, m;
cij:=T[i][j];
pos:=Position(cij[1],k);
if pos=fail then
return T[Length(T)];
else
if S=[] then
return cij[2][pos];
else
if Length( map[1] )>0 and not (S[a][b][c] in F
or IsRat(S[a][b][c]) ) then
# Here `p' is a polynomial in the variables used in
# stringtabs, we produce the same polynomial, but in
# the variables used in the ideal; it all boils down
# to renumbering of variables...
p:= ExtRepPolynomialRatFun( S[a][b][c] );
ef:= [ ];
for l in [1,3..Length(p)-1] do
mon:= ShallowCopy( p[l] );
for m in [1,3..Length(mon)-1] do
pos:= Position( map[1], mon[m] );
mon[m]:= map[2][pos];
od;
Add( ef, mon );
Add( ef, p[l+1] );
od;
return PolynomialByExtRep( FamilyObj( S[a][b][c] ), ef );
else
return S[a][b][c];
fi;
fi;
fi;
end;
filt:=function( b1, b2 )
local sp;
sp:=VectorSpace(F,b2);
return Filtered(b1,y -> y in sp);
end;
n:=Dimension(L1);
if n <> Dimension( L2 ) then return false; fi;
F:=LeftActingDomain(L1);
if F <> LeftActingDomain( L2 ) then return false; fi;
if StructureConstantsTable( Basis( L1 ) ) =
StructureConstantsTable( Basis( L2 ) ) then
return true;
fi;
if Dimension(LieCentre(L1)) <> Dimension(LieCentre(L2)) then
return false;
fi;
if Dimension(LieDerivedSubalgebra(L1))<>
Dimension(LieDerivedSubalgebra(L2)) then
return false;
fi;
ser1:=LieLowerCentralSeries(L1);
ser2:=LieLowerCentralSeries(L2);
if List(ser1,V->Dimension(V))<>List(ser2,V->Dimension(V)) then
return false;
fi;
dser1:=LieDerivedSeries(L1);
dser2:=LieDerivedSeries(L2);
if List(dser1,V->Dimension(V))<>List(dser2,V->Dimension(V)) then
return false;
fi;
## if not IsLieNilpotent(L1) then
H1:= CartanSubalgebra( L1 );
if Dimension(H1) = n then
cart1:= [ L1 ];
else
cart1:= [ L1, H1 ];
fi;
H2:= CartanSubalgebra( L2 );
if Dimension( H2 ) = n then
cart2:= [ L2 ];
else
cart2:= [ L2, H2 ];
fi;
if Dimension(H1) <> Dimension(H2) then return false; fi;
lev1:= ShallowCopy( LeviMalcevDecomposition(L1) ); Add( lev1, L1 );
lev2:= ShallowCopy( LeviMalcevDecomposition(L2) ); Add( lev2, L2 );
lev1:= Filtered( lev1, x->Dimension(x)<>0 );
lev2:= Filtered( lev2, x->Dimension(x)<>0 );
if List(lev1,V->Dimension(V))<>List(lev2,V->Dimension(V)) then
return false;
fi;
nrad1:= [ L1 ];
if not IsLieNilpotent( L1 ) then
Append( nrad1, LieLowerCentralSeries( LieNilRadical( L1 ) ) );
Append( nrad1, LieUpperCentralSeries( LieNilRadical( L1 ) ) );
fi;
nrad1:= Filtered( nrad1, x->Dimension(x)<>0 );
nrad2:= [ L2 ];
if not IsLieNilpotent( L2 ) then
Append( nrad2, LieLowerCentralSeries( LieNilRadical( L2 ) ) );
Append( nrad2, LieUpperCentralSeries( LieNilRadical( L2 ) ) );
fi;
nrad2:= Filtered( nrad2, x->Dimension(x)<>0 );
if List(nrad1,V->Dimension(V))<>List(nrad2,V->Dimension(V)) then
return false;
fi;
if not IsLieNilpotent(L1) then
HL1:= ProductSpace( H1, L1 );
while Dimension(H1)+Dimension(HL1) > Dimension(L1) do
HL1:= ProductSpace( H1, HL1 );
od;
adH1:= [ ];
for i in BasisVectors(Basis(H1)) do
mat:= List( BasisVectors(Basis(HL1)),
x -> Coefficients( Basis(HL1), i*x ) );
Add( adH1, TransposedMat( mat ) );
od;
HL2:= ProductSpace( H2, L2 );
while Dimension(H2)+Dimension(HL2) > Dimension(L2) do
HL2:= ProductSpace( H2, HL2 );
od;
adH2:= [ ];
for i in BasisVectors(Basis(H2)) do
mat:= List( BasisVectors(Basis(HL2)),
x -> Coefficients( Basis(HL2), i*x ) );
Add( adH2, TransposedMat( mat ) );
od;
Add( adH1, IdentityMat( Dimension(HL1), F ) );
Add( adH2, IdentityMat( Dimension(HL2), F ) );
A1:= Algebra( F, adH1 );
A2:= Algebra( F, adH2 );
if Dimension(A1)<>Dimension(A2) then return false; fi;
R1:= RadicalOfAlgebra( A1 );
R2:= RadicalOfAlgebra( A2 );
if Dimension(R1)<>Dimension(R2) then return false; fi;
B1:=A1/R1; B2:=A2/R2;
C1:= CentralIdempotentsOfAlgebra( B1 );
C2:= CentralIdempotentsOfAlgebra( B2 );
if Length(C1)<>Length(C2) then return false; fi;
Id1:=[];
for i in C1 do
b:= List( BasisVectors(Basis(B1)), x -> x*i );
Add( Id1, Dimension( VectorSpace( F, b ) ) );
od;
Id2:=[];
for i in C2 do
b:= List( BasisVectors(Basis(B2)), x -> x*i );
Add( Id2, Dimension( VectorSpace( F, b ) ) );
od;
for i in Id1 do
if not i in Id2 then return false; fi;
od;
fi;
if Dimension(Derivations(Basis(L1))) <>
Dimension(Derivations(Basis(L2))) then
return false;
fi;
cen1:=ShallowCopy(LieUpperCentralSeries(L1));
cen2:=ShallowCopy(LieUpperCentralSeries(L2));
Add(cen1,L1); Add(cen2,L2);
if List(cen1,V->Dimension(V))<>List(cen2,V->Dimension(V)) then
return false;
fi;
ser1:=Filtered(ser1,x->Dimension(x)<>0);
ser2:=Filtered(ser2,x->Dimension(x)<>0);
cen1:=Filtered(cen1,x->Dimension(x)<>0);
cen2:=Filtered(cen2,x->Dimension(x)<>0);
dser1:=Filtered(dser1,x->Dimension(x)<>0);
dser2:=Filtered(dser2,x->Dimension(x)<>0);
spaces1:=[];
inds:=[];
for i in [1..Length(dser1)] do
for j in [1..Length(ser1)] do
sp:=Intersection(dser1[Length(dser1)-i+1],ser1[Length(ser1)-j+1]);
for k in [1..Length(cen1)] do
sp1:=Intersection(sp,cen1[Length(cen1)-k+1]);
for l in [1..Length(cart1)] do
sp2:= Intersection( sp1, cart1[l] );
for m in [1..Length(lev1)] do
sp3:= Intersection( sp2, lev1[m] );
for r in [1..Length(nrad1)] do
sp4:= Intersection( sp3, nrad1[r] );
if not sp4 in spaces1 and Dimension(sp4) <> 0 then
Add(spaces1,sp4);
Add(inds,[i,j,k,l,m,r]);
fi;
od;
od;
od;
od;
od;
od;
SortParallel( spaces1, inds, function(V1,V2)
return Dimension(V1)<Dimension(V2); end );
spaces2:=[];
for s in [1..Length(inds)] do
i:=inds[s][1]; j:=inds[s][2]; k:=inds[s][3]; l:=inds[s][4];
m:=inds[s][5]; r:=inds[s][6];
sp:=Intersection(dser2[Length(dser2)-i+1],ser2[Length(ser2)-j+1]);
sp1:= Intersection( sp, cen2[Length(cen2)-k+1] );
sp2:= Intersection( sp1, cart2[l] );
sp3:= Intersection( sp2, lev2[m] );
sp4:= Intersection( sp3, nrad2[r] );
Add(spaces2,sp4);
od;
bas1:=List(spaces1,V->BasisVectors(Basis(V)));
bas2:=List(spaces2,V->BasisVectors(Basis(V)));
if List(spaces1,x->Dimension(x))<>List(spaces2,x->Dimension(x)) then
return false;
fi;
# The next piece of code selects a minimal number of subspaces from
# 'bas1' and 'bas2' such that they span 'L1' and 'L2' respectively.
b:=ShallowCopy(bas1[1]); sp:=VectorSpace(F,b); pp:=[1];
for k in [2..Length(bas1)] do
cont:=true;
for l in [1..Length(bas1[k])] do
if not bas1[k][l] in sp then
cont:=false;
Add(b,bas1[k][l]);
fi;
od;
if not cont then
Add(pp,k); sp:=VectorSpace(F,b);
fi;
od;
bas1:=List(pp,ii->bas1[ii]);
bas2:=List(pp,ii->bas2[ii]);
# After the next piece of code, 'bb1' will be a basis of 'L1' and
# 'i1[k]' will be the index of the element of 'bas1' that contains
# 'bb1[k]' (similarly for 'bb2' and 'i2).
bb1:=[]; bb2:=[];
sp1:=VectorSpace(F,[Zero(L1)]); sp2:=VectorSpace(F,[Zero(L2)]);
i1:=[]; i2:=[];
for l in [1..Length(bas1)] do
for k in [1..Length(bas1[l])] do
x:=bas1[l][k];
if not x in sp1 then Add(bb1,x);
sp1:=VectorSpace(F,bb1); Add(i1,l); fi;
x:=bas2[l][k];
if not x in sp2 then Add(bb2,x);
sp2:=VectorSpace(F,bb2); Add(i2,l); fi;
od;
od;
# The next statement ensures that all elements of 'bas1' contain elements of
# 'bb1'.
bas1:=List(bas1,bb->filt(bb1,bb));
bas2:=List(bas2,bb->filt(bb2,bb));
# Print the isomorphism...
if InfoLevel( InfoSingular )>=2 then
sp := VectorSpace( F, [Zero(L1)] );
b:=[];
m:=0;
for k in [1..Length(bas1)] do
for l in [1..Length(bas1[k])] do
x:=bas1[k][l];
if not x in sp then
Add(b,x);
sp:=VectorSpace( F, b );
m:=m+1;
Print( x, " ---> " );
for i in [1..Length(bas2[k])] do
j:= Position( bb2, bas2[k][i] );
Print( "x[",m,",",j,"](",bas2[k][i],") " );
if i<Length(bas2[k]) then Print("+ "); fi;
od;
Print("\n");
fi;
od;
od;
Print("\n");
fi;
ii1:=List( bb1, x -> Position( BasisVectors(Basis(L1)), x ) );
T1:=StructureConstantsTable(Basis(L1,bb1));
T2:=StructureConstantsTable(Basis(L2,bb2));
if T1 = T2 then
return true;
fi;
vars:= [ ];
for i in [1..Length(bas1)] do
vars[i]:= "d"; Append( vars[i], String(i) );
od;
for i in [1..n] do
for j in [1..n] do
str:= "x"; Append( str, String( i ) ); Append( str, String( j ) );
Add( vars, str );
od;
od;
if S <> [ ] then
for i in [1..npar] do
str:= "a"; Append( str, String( i ) );
Add( vars, str );
od;
fi;
weights:= [ ];
for i in [1..Length(bas1)] do
Add( weights, Length(bas1[i]) );
od;
for i in [1..n^2] do Add( weights, 1 ); od;
if S<>[] then
for i in [1..npar] do Add( weights, 5 ); od;
fi;
R:= PolynomialRing( F, vars : old );
indets:= IndeterminatesOfPolynomialRing( R );
# varlist:=[a1,a2,a3];
# `map' is used to identify the indeterminates used in the stringtabs,
# with the indeterminates used in the ideal...
map:= [ List( varlist, x -> ExtRepPolynomialRatFun(x)[1][1]),
List( indets{[Length(indets)-npar+1..Length(indets)]}, x ->
ExtRepPolynomialRatFun(x)[1][1]) ];
# Construct the matrices of which the determinants must go into the ideal.
# variable x_{ij} has number Length(bas1)+ (i-1)*n +j
d:=0; b:=[]; sp:=VectorSpace(F,[Zero(L1)]); mats:= [ ];
for k in [1..Length(bas1)] do
bass1:=Filtered(bas1[k],v-> not v in sp );
l:=Length(bass1)+d;
M:= List( [d+1..l], x -> [] );
for i in [d+1..l] do
for j in [d+1..l] do
M[i-d][j-d]:= indets[Length(bas1)+(i-1)*n+j];
od;
od;
Add( mats, M );
d:=l; Append(b,bass1); sp:=VectorSpace(F,b);
od;
# Get the generators of the ideal...
I:= [ ];
for k in [1..n] do
ll1:=List(bas2[i2[k]],y->Position(bb2,y));
for l in [1..k-1] do
p:= Zero( R );
ll2:=List(bas2[i2[l]],y->Position(bb2,y));
for o in [1..n] do
fl:=0;
for j in [1..n] do
for m in [1..n] do
c:=cst(T2,[],j,m,o,0,0,0,map);
if c<>Zero(F) then
if j in ll1 and m in ll2 then
p:= p+ c*indets[Length(bas1)+(k-1)*n+j]*
indets[Length(bas1)+(l-1)*n+m];
fl:=1;
fi;
fi;
od;
od;
for j in [1..n] do
c:=cst(T1,S,l,k,j,ii1[l],ii1[k],ii1[j],map);
ll3:=List(bas2[i2[j]],y->Position(bb2,y));
if c<>Zero(F) and o in ll3 then
p:=p+c*indets[Length(bas1)+(j-1)*n+o];
fl:=1;
fi;
od;
if fl=1 then
Add( I, p );
p:=Zero( R );
fi;
od;
od;
od;
for k in [1..Length(bas1)] do
p:= indets[k]*DeterminantMat( mats[k] )-1;
Add( I, p );
od;
return [R,I,weights];
end );
BindGlobal( "LieIsomorphismCharP", function(L1,L2,S,varlist)
local cst, filt, n, F, ser1, ser2, cen1, cen2, dser1, dser2,
# H1, cart1, H2, cart2, lev1, lev2,
# HL1, adH1, mat, HL2, adH2, A1, A2, R1,
# R2, B1, B2, C1, C2, Id1, b, Id2,
nrad1, nrad2, i, b, spaces1, inds,
j, sp, k, sp1, l, sp2, m, sp3, r, sp4, spaces2,
s, bas1, bas2, pp, cont, bb1, bb2, i1, i2, x,
ii1, T1, T2, vars, str, weights, R, indets,
map, d, mats, bass1, M, I, ll1, p, ll2,
o, fl, c, ll3, npar;
npar:= Length( varlist );
cst:=function(T,S,i,j,k,a,b,c,map)
local cij, pos, p, ef, l, mon, m;
cij:=T[i][j];
pos:=Position(cij[1],k);
if pos=fail then
return T[Length(T)];
else
if S=[] then
return cij[2][pos];
else
if Length( map[1] )>0 and not (S[a][b][c] in F
or IsRat(S[a][b][c]) ) then
# Here `p' is a polynomial in the variables used in
# stringtabs, we produce the same polynomial, but in
# the variables used in the ideal; it all boils down
# to renumbering of variables...
p:= ExtRepPolynomialRatFun( S[a][b][c] );
ef:= [ ];
for l in [1,3..Length(p)-1] do
mon:= ShallowCopy( p[l] );
for m in [1,3..Length(mon)-1] do
pos:= Position( map[1], mon[m] );
mon[m]:= map[2][pos];
od;
Add( ef, mon );
Add( ef, p[l+1] );
od;
return PolynomialByExtRep( FamilyObj( S[a][b][c] ), ef );
else
return S[a][b][c];
fi;
fi;
fi;
end;
filt:=function( b1, b2 )
local sp;
sp:=VectorSpace(F,b2);
return Filtered(b1,y -> y in sp);
end;
n:=Dimension(L1);
if n <> Dimension( L2 ) then return false; fi;
F:=LeftActingDomain(L1);
if F <> LeftActingDomain( L2 ) then return false; fi;
if StructureConstantsTable( Basis( L1 ) ) =
StructureConstantsTable( Basis( L2 ) ) then
return true;
fi;
if Dimension(LieCentre(L1)) <> Dimension(LieCentre(L2)) then
return false;
fi;
if Dimension(LieDerivedSubalgebra(L1))<>
Dimension(LieDerivedSubalgebra(L2)) then
return false;
fi;
ser1:=LieLowerCentralSeries(L1);
ser2:=LieLowerCentralSeries(L2);
if List(ser1,V->Dimension(V))<>List(ser2,V->Dimension(V)) then
return false;
fi;
dser1:=LieDerivedSeries(L1);
dser2:=LieDerivedSeries(L2);
if List(dser1,V->Dimension(V))<>List(dser2,V->Dimension(V)) then
return false;
fi;
nrad1:= [ L1 ];
if not IsLieNilpotent( L1 ) then
Append( nrad1, LieLowerCentralSeries( LieNilRadical( L1 ) ) );
Append( nrad1, LieUpperCentralSeries( LieNilRadical( L1 ) ) );
fi;
nrad1:= Filtered( nrad1, x->Dimension(x)<>0 );
nrad2:= [ L2 ];
if not IsLieNilpotent( L2 ) then
Append( nrad2, LieLowerCentralSeries( LieNilRadical( L2 ) ) );
Append( nrad2, LieUpperCentralSeries( LieNilRadical( L2 ) ) );
fi;
nrad2:= Filtered( nrad2, x->Dimension(x)<>0 );
if List(nrad1,V->Dimension(V))<>List(nrad2,V->Dimension(V)) then
return false;
fi;
if Dimension(Derivations(Basis(L1))) <>
Dimension(Derivations(Basis(L2))) then
return false;
fi;
cen1:=ShallowCopy(LieUpperCentralSeries(L1));
cen2:=ShallowCopy(LieUpperCentralSeries(L2));
Add(cen1,L1); Add(cen2,L2);
if List(cen1,V->Dimension(V))<>List(cen2,V->Dimension(V)) then
return false;
fi;
ser1:=Filtered(ser1,x->Dimension(x)<>0);
ser2:=Filtered(ser2,x->Dimension(x)<>0);
cen1:=Filtered(cen1,x->Dimension(x)<>0);
cen2:=Filtered(cen2,x->Dimension(x)<>0);
dser1:=Filtered(dser1,x->Dimension(x)<>0);
dser2:=Filtered(dser2,x->Dimension(x)<>0);
spaces1:=[];
inds:=[];
for i in [1..Length(dser1)] do
for j in [1..Length(ser1)] do
sp:=Intersection(dser1[Length(dser1)-i+1],ser1[Length(ser1)-j+1]);
for k in [1..Length(cen1)] do
sp1:=Intersection(sp,cen1[Length(cen1)-k+1]);
for r in [1..Length(nrad1)] do
sp4:= Intersection( sp1, nrad1[r] );
if not sp4 in spaces1 and Dimension(sp4) <> 0 then
Add(spaces1,sp4);
Add(inds,[i,j,k,r]);
fi;
od;
od;
od;
od;
SortParallel( spaces1, inds, function(V1,V2)
return Dimension(V1)<Dimension(V2); end );
spaces2:=[];
for s in [1..Length(inds)] do
i:=inds[s][1]; j:=inds[s][2]; k:=inds[s][3]; r:=inds[s][4];
sp:=Intersection(dser2[Length(dser2)-i+1],ser2[Length(ser2)-j+1]);
sp1:= Intersection( sp, cen2[Length(cen2)-k+1] );
sp4:= Intersection( sp1, nrad2[r] );
Add(spaces2,sp4);
od;
bas1:=List(spaces1,V->BasisVectors(Basis(V)));
bas2:=List(spaces2,V->BasisVectors(Basis(V)));
if List(spaces1,x->Dimension(x))<>List(spaces2,x->Dimension(x)) then
return false;
fi;
# The next piece of code selects a minimal number of subspaces from
# 'bas1' and 'bas2' such that they span 'L1' and 'L2' respectively.
b:=ShallowCopy(bas1[1]); sp:=VectorSpace(F,b); pp:=[1];
for k in [2..Length(bas1)] do
cont:=true;
for l in [1..Length(bas1[k])] do
if not bas1[k][l] in sp then
cont:=false;
Add(b,bas1[k][l]);
fi;
od;
if not cont then
Add(pp,k); sp:=VectorSpace(F,b);
fi;
od;
bas1:=List(pp,ii->bas1[ii]);
bas2:=List(pp,ii->bas2[ii]);
# After the next piece of code, 'bb1' will be a basis of 'L1' and
# 'i1[k]' will be the index of the element of 'bas1' that contains
# 'bb1[k]' (similarly for 'bb2' and 'i2).
bb1:=[]; bb2:=[];
sp1:=VectorSpace(F,[Zero(L1)]); sp2:=VectorSpace(F,[Zero(L2)]);
i1:=[]; i2:=[];
for l in [1..Length(bas1)] do
for k in [1..Length(bas1[l])] do
x:=bas1[l][k];
if not x in sp1 then Add(bb1,x);
sp1:=VectorSpace(F,bb1); Add(i1,l); fi;
x:=bas2[l][k];
if not x in sp2 then Add(bb2,x);
sp2:=VectorSpace(F,bb2); Add(i2,l); fi;
od;
od;
# The next statement ensures that all elements of 'bas1' contain elements of
# 'bb1'.
bas1:=List(bas1,bb->filt(bb1,bb));
bas2:=List(bas2,bb->filt(bb2,bb));
# Print the isomorphism...
if InfoLevel( InfoSingular )>=2 then
sp := VectorSpace( F, [Zero(L1)] );
b:=[];
m:=0;
for k in [1..Length(bas1)] do
for l in [1..Length(bas1[k])] do
x:=bas1[k][l];
if not x in sp then
Add(b,x);
sp:=VectorSpace( F, b );
m:=m+1;
Print( x, " ---> " );
for i in [1..Length(bas2[k])] do
j:= Position( bb2, bas2[k][i] );
Print( "x[",m,",",j,"](",bas2[k][i],") " );
if i<Length(bas2[k]) then Print("+ "); fi;
od;
Print("\n");
fi;
od;
od;
Print("\n");
fi;
ii1:=List( bb1, x -> Position( BasisVectors(Basis(L1)), x ) );
# Ugly workaround for char p
# try LookUp( SmallLieAlgebra( GF(5), 5, 56 ) );
while fail in ii1 do
Print( "WARNING: using ugly workaround!\n", ii1 );
ii1[Position( ii1, fail )]
:= Difference( [ 1 .. Length( ii1 ) ], ii1 )[1];
Print( " --> ", ii1, "\n" );
od;
T1:=StructureConstantsTable(Basis(L1,bb1));
T2:=StructureConstantsTable(Basis(L2,bb2));
if T1 = T2 then
return true;
fi;
vars:= [ ];
for i in [1..Length(bas1)] do
vars[i]:= "d"; Append( vars[i], String(i) );
od;
for i in [1..n] do
for j in [1..n] do
str:= "x"; Append( str, String( i ) ); Append( str, String( j ) );
Add( vars, str );
od;
od;
if S <> [ ] then
for i in [1..npar] do
str:= "a"; Append( str, String( i ) );
Add( vars, str );
od;
fi;
weights:= [ ];
for i in [1..Length(bas1)] do
Add( weights, Length(bas1[i]) );
od;
for i in [1..n^2] do Add( weights, 1 ); od;
if S<>[] then
for i in [1..npar] do Add( weights, 5 ); od;
fi;
R:= PolynomialRing( F, vars : old );
indets:= IndeterminatesOfPolynomialRing( R );
# varlist:=[a1,a2,a3];
# `map' is used to identify the indeterminates used in the stringtabs,
# with the indeterminates used in the ideal...
map:= [ List( varlist, x -> ExtRepPolynomialRatFun(x)[1][1]),
List( indets{[Length(indets)-npar+1..Length(indets)]}, x ->
ExtRepPolynomialRatFun(x)[1][1]) ];
# Construct the matrices of which the determinants must go into the ideal.
# variable x_{ij} has number Length(bas1)+ (i-1)*n +j
d:=0; b:=[]; sp:=VectorSpace(F,[Zero(L1)]); mats:= [ ];
for k in [1..Length(bas1)] do
bass1:=Filtered(bas1[k],v-> not v in sp );
l:=Length(bass1)+d;
M:= List( [d+1..l], x -> [] );
for i in [d+1..l] do
for j in [d+1..l] do
M[i-d][j-d]:= indets[Length(bas1)+(i-1)*n+j];
od;
od;
Add( mats, M );
d:=l; Append(b,bass1); sp:=VectorSpace(F,b);
od;
# Get the generators of the ideal...
I:= [ ];
for k in [1..n] do
ll1:=List(bas2[i2[k]],y->Position(bb2,y));
for l in [1..k-1] do
p:= Zero( R );
ll2:=List(bas2[i2[l]],y->Position(bb2,y));
for o in [1..n] do
fl:=0;
for j in [1..n] do
for m in [1..n] do
c:=cst(T2,[],j,m,o,0,0,0,map);
if c<>Zero(F) then
if j in ll1 and m in ll2 then
p:= p+ c*indets[Length(bas1)+(k-1)*n+j]*
indets[Length(bas1)+(l-1)*n+m];
fl:=1;
fi;
fi;
od;
od;
for j in [1..n] do
c:=cst(T1,S,l,k,j,ii1[l],ii1[k],ii1[j],map);
ll3:=List(bas2[i2[j]],y->Position(bb2,y));
if c<>Zero(F) and o in ll3 then
p:=p+c*indets[Length(bas1)+(j-1)*n+o];
fl:=1;
fi;
od;
if fl=1 then
Add( I, p );
p:=Zero(R);
fi;
od;
od;
od;
for k in [1..Length(bas1)] do
p:= indets[k]*DeterminantMat( mats[k] )-1;
Add( I, p );
od;
return [R,I,weights];
end );
BindGlobal( "LookUp", function( L )
local F,i,K,file,n,lst,slist,look,ff,dd,pb,G,
lie_tables, varlist,
gens, pol, eli, roots;
dd:= DirectSumDecomposition(L);
if Length(dd)>1 then
Print("Perform a direct sum decomposition first\n");
Print("using the function DirectSumDecomposition\n");
Print("and try to identify the direct summands.\n");
else
F:=LeftActingDomain(L);
n:= Dimension(L);
if n=0 or n=1 then
# the Lie algebra is the unique 0- or 1-dimensional Lie algebra
return 1;
fi;
lie_tables:= LieTables( F, n, [] );
lst:= lie_tables[1];
slist:= lie_tables[2];
varlist:= lie_tables[3];
Info(InfoSingular, 2, "Looking for L in the list dim", n );
for i in [1..Length(lst)] do
if StructureConstantsTable(Basis(L)) = lst[i] then
return i;
fi;
K:= LieAlgebraByStructureConstants(F, lst[i]);
if Characteristic( F ) = 0 then
pb:=LieIsomorphism( K, L, slist[i], varlist);
else
pb:=LieIsomorphismCharP( K, L, slist[i], varlist);
fi;
if IsList( pb ) then
if not HasTrivialGroebnerBasis (Ideal( pb[1], pb[2] )) then
# The following is experimental code that suggests the value of the
# parameter for a Lie algebra isomorphic to one in a one-parameter family
# of Lie algebras.
if Length( slist[i] )>1 and Length( varlist ) = 1 then
gens := GeneratorsOfLeftOperatorRingWithOne( pb[1] );
# the other indeterminates (not the parameter) are the following
pol := Product( gens{[ 1 .. Length( gens ) - 1 ]} );
# the other indeterminates are eliminated by Singular
pol := ParseGapPolyToSingPoly( pol );
eli := SingularInterface( "eliminate",
Concatenation( "GAP_groebner, ", pol ), "ideal" );
gens := GeneratorsOfTwoSidedIdeal( eli );
if Length( gens ) = 1 and
IsUnivariatePolynomial( gens[1] ) and
Degree( gens[1] ) <> 0 and
Degree( gens[1] ) <> infinity then
# We have an equation in the parameter
roots := RootsOfUPol( F, gens[1] );
if Length(roots) <> 0 then
Print( "PARAMETER: one in ", roots, "\n" );
else
# maybe the parameter is not in the underlying field of the algebra
# in this case the algebras are only "weakly" isomorphic!
roots := RootsOfUPol( "split",gens[1] );
Print( "PARAMETER: (in splitting field) one in ",
roots, "\n" );
fi;
fi;
fi;
# end of experimental code
return i;
fi;
elif pb = true then
return i;
fi;
od;
if TestJacobi(StructureConstantsTable(Basis(L)))<> true then
return "not a Lie algebra (TestJacobi) ";
elif not ForAll( List( Basis(L), x->x*x ), x->x=Zero(L) ) then
return "not a Lie algebra (IsZeroSquaredRing) ";
fi;
return fail;
fi;
end );
BindGlobal( "Compare", function ( L, n )
# This function compares the Lie algebra L with the n-th element of the
# data of the Lie algebras, and return the ideal in which the Groebner
# basis can be calculated.
local F, d, s, K, pb;
F := LeftActingDomain( L );
d := Dimension( L );
s := LieTables( F, d, [ ] );
K := LieAlgebraByStructureConstants( F, s[1][n] );
if Characteristic( F ) = 0 then
pb := LieIsomorphism( K, L, s[2][n], s[3] );
else
pb := LieIsomorphismCharP( K, L, s[2][n], s[3] );
fi;
return pb;
end );
BindGlobal( "AreIsomorphic", function( K, L )
# Test whether the Lie algebras K, L are isomorphic.
local char, pb;
char:= Characteristic( LeftActingDomain( K ) );
if char = 0 then
pb:=LieIsomorphism( K, L, [], []);
else
pb:=LieIsomorphismCharP( K, L, [], []);
fi;
if IsList( pb ) then
return not HasTrivialGroebnerBasis( Ideal( pb[1], pb[2] ) );
else
return pb;
fi;
end );
BindGlobal( "AreSimilar", function( K, L )
# Test whether the Lie algebras K, L are similar.
local char, pb;
char:= Characteristic( LeftActingDomain( K ) );
if char = 0 then
pb:=LieIsomorphism( K, L, [], []);
else
pb:=LieIsomorphismCharP( K, L, [], []);
fi;
if IsList( pb ) then
return true;
else
return pb;
fi;
end );
[ Dauer der Verarbeitung: 0.47 Sekunden
(vorverarbeitet)
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