A neural network model capable of self-organizing in presence of multi
ple or mixed categories is presented. A certainty factor is derived ab
out the decision on how well the features (due to single or mixed cate
gories) have been interpreted by the network. One part of the model, t
he, monitor, controls the performance of the other part, the, categori
zer in the self-organization process. The network automatically adjust
s the number of nodes in the hidden and output layers, depending on th
e nature of overlap between the patterns from different categories. Ma
thematical derivations of the bounds on the number of nodes have been
presented. The capability of the model is demonstrated experimentally
both on one-dimensional binary strings and visual patterns.