Creating New Root Systems from Old

R1 + R2 : RootSys, RootSys -> RootSys

DirectSum( R1, R2 ) : RootSys, RootSys -> RootSys

The direct sum of the root systems R_1 and R_2.

Dual( R ) : RootSys -> RootSys

The dual of the root system R, obtained by swapping the roots and coroots.

Example RootSys_DirectSumDual (H79E16)

> R1 := RootSystem( "H4" );
> R2 := RootSystem( "B4" );
> R1 + Dual( R2 );