Source : Free On-Line Dictionary of Computing

pattern recognition
     
         A branch of
        {artificial intelligence} concerned with the classification or
        description of observations.
     
        Pattern recognition aims to classify {data} (patterns) based
        on either a priori knowledge or on statistical information
        extracted from the patterns.  The patterns to be classified
        are usually groups of measurements or observations, defining
        points in an appropriate multidimensional space.
     
        A complete pattern recognition system consists of a sensor
        that gathers the observations to be classified or described; a
        {feature extraction} mechanism that computes numeric or
        {symbolic} information from the observations; and a
        classification or description scheme that does the actual job
        of classifying or describing observations, relying on the
        extracted features.
     
        The classification or description scheme is usually based on
        the availability of a set of patterns that have already been
        classified or described.  This set of patterns is termed the
        {training set} and the resulting learning strategy is
        characterised as {supervised}.  Learning can also be
        {unsupervised}, in the sense that the system is not given an a
        priori labelling of patterns, instead it establishes the
        classes itself based on the statistical regularities of the
        patterns.
     
        The classification or description scheme usually uses one of
        the following approaches: statistical (or {decision
        theoretic}), syntactic (or structural), or neural.
        Statistical pattern recognition is based on statistical
        characterisations of patterns, assuming that the patterns are
        generated by a {probabilistic} system.  Structural pattern
        recognition is based on the structural interrelationships of
        features.  Neural pattern recognition employs the neural
        computing paradigm that has emerged with {neural networks}.
     
        (1995-09-22)