Classifier (mathematics)

In mathematics, a classifier is a mapping from a (discrete or continuous) feature space X to a discrete set of labels Y.

Classifiers may either be fixed classifiers or learning classifiers, and learning classifiers may in turn be divided into supervised and unsupervised learning classifiers.

There are a number of different types of classifier technologies:

• Bayesian classifiers
• Support vector machines
• k-nearest neighbor classifiers
• neural network classifiers
• linear classifiers
• quadratic classifiers

Classifiers are used in many practical applications, including optical character recognition, speech recognition and handwriting recognition, biometric identification and Internet search engines.