Discrimination problems in a high-dimensional setting is considered. New re
sults are concerned with the role of the dimensionality in the performance
of the discrimination procedure. Assuming that data consist of a block stru
cture two different asymptotic approaches are presented. These approaches a
re characterized by different types of relations between the dimensionality
and the size of the training samples. Asymptotic expressions for the error
probabilities are obtained and a consistent approximation of the discrimin
ant function is proposed. Throughout the paper the importance of the dimens
ionality in the asymptotic analysis is stressed.