[PPL-devel] something not clear...

Hi, i've started to read the ppl documentation, and i've found a doubt reading section at page 8: 1.4.5 Removing Dimensions from the vector space. and in particular, how the remove_space_dimension works. In fact from the example i can not understand why applying the operator on the singleton set {(3,1,0,2)^T} in R^4 with the variable set {x_1, x_2} we obtain just {(3,2)^T}. Namely, i can not understand which is the connection between the set of variables gived to the operator and the two dimensions removed from P (i.e the second and the third). Instead, the remove_higher_space_dimension operator is simpler because is easy to understand that it removes all the dimensions i >= m. Thanks, Alessandro Vincenzi