“…The Lie algebra so (p, q) of SO(p, q) may then be defined as the set of real (p + q) x (p + q) matrices a such that tr a = 0 and ag+ga=0 (1.1) Even in two closely related problems it can happen that the so (p, q) basis is the most useful for one problem while the canonical basis is the most convenient for the other. For example, the recent determination of the maximal solvable subgroups of SO(p, q) by Patera, Winternitz & Zassenhaus (1974) employs the so(p, q) basis, while for embeddings of SO(p, q) with other semi-simple Lie groups (Cornwell, 1971a(Cornwell, , 1971bEkins & Comwell, 1974a, 1974b, 1974c) the canonical basis is the most convenient.…”