Multiple Classes

• What can you do when there are, say, four classes.
• You could make a tree of binary classifiers (1 and 2) vs. (3 and 4), then 1 vs. 2 and 3 vs. 4.
• Would this work for 10 classes, or 137.
• Note you can see one of the many benefits of hierarchy here.
• There are smarter things you can do, but you can see how binary classifiers cover a lot of ground.
• It is an important foundation of learning.
• Modern machine learning has solid mathematical foundations. The line (and linear and hyper planar separators) are basic bulding blocks.