Hi. 1. Can anyone definitively tell me what the dimension formula for the classical Lie algebras? For example, I know for SO(2n) or D_n, the dimension formula is SO(N)--> (N*(N-1))/2 E.g. SO(8) is 8*7/2 = 28. Ok, so what about SU(N+1) i.e. A_n, SO(2n+1) i.e. B_N and Sp(n) i.e. C_n ? 2. I have (using # of simple roots = the rank ) that # total roots = dim (above) - rank and therefore the # of positive roots is half of this quantity (i.e. (dim-rank)/2 ) Any help would be great. Thanks!