Gamma: The Learned Classifier
In machine learning and statistics, classification is the problem of identifying a semantic class for an observation, on the basis of a training set of data containing observations (or instances) whose class membership is known.
a learned classifier:
Gamma is a classifier, that given a document, will give us the class that document belongs to (with an associated degree of probability to boot!). Our job is the build the function gamma, which takes a document, and returns a class.