parabolic(RootSystem,Set) -- construct a parabolic from a set of simple roots

• Function: parabolic

• Usage:

  parabolic(R,S)

• Inputs:
  • R, an instance of the type RootSystem,
  • S, a set, the subsets of simple roots defining the standard parabolic
• Outputs:
  • an instance of the type Parabolic, a standard parabolic subgroup represented by a set of simple roots

i1 : parabolic(rootSystemA(5),set{1,2})

o1 = set {1, 2}

o1 : Parabolic