Pruning methods train a larger-than-necessary
network and then remove unneeded elements. The opposite approach is to build a
network incrementally, adding elements until a suitable configuration is found.
The two approaches are complementary and often used together. Like pruning, constructive
techniques are a means of adjusting the size of a network rather than a method
for deciding what size is appropriate. Other criteria are still necessary to decide
when to stop adding elements. A number of constructive methods are discussed in
chapter 12. Cascade-correlation  is often cited as an