7.7 integrating neural networks and knowledge-Based systeMs 209
adjusting the input-layer weights using the generalized delta rule, each train-
ing input pattern is used as the connection weights to a new hidden unit.
Actually, each input pattern is integrated into the PNN architecture. This
technique is extremely fast, because only one pass through the network is re-
quired to set the input connection weights. Additional passes might be used
to adjust the output weights to fine-tune the network outputs.
Many researchers have claimed that adding a hidden unit for each input
pattern might be overkill. Several clustering schemes have been proposed
to cut down on the number of hidden units when input patterns are close
in input space ...