The Quantum Frobenius Homomorphism
G. Lusztig · Birkhäuser Boston eBooks · 2010
35.1.1. In this chapter we fix an integer I ≥ 1. Then the integers l i ≥ 1, the new Cartan datum (I, o) and the new root datum (Y*,X*,…) of type (I, o) are defined in terms of l, (I, ·), (Y, X,…) as in 2.2.4, 2.2.5.