DeclareAttribute( "RegularSemisimpleSubalgebras", IsLieAlgebra );

DeclareAttribute( "ClosedSubsets", IsRootSystem );

DeclareOperation( "IsSpecialClosedSet", [ IsList ] );

DeclareOperation( "DecompositionOfClosedSet", [ IsList ] );

DeclareOperation( "SubalgebraOfClosedSet", [ IsLieAlgebra, IsList ] );