Pattern Recognition book: Chapter(1)

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Pattern Recognition



  • Introduction

Machine Perception

  • Build a machine that can recognize patterns:
    • Speech recognition
    • Fingerprint identification
    • OCR (Optical Character Recognition)
    • DNA sequence identification
  • Better decision boundary

Learning and Adaptation

  • Supervised learning
    • A teacher provides a category label for each pattern in the training set
  • Unsupervised learning
    • The system forms clusters or “natural groupings” of the unlabeled input patterns
  • Reinforcement learning or learning with a critic,
  • no desired category signal is given; critic instead, the only teaching feedback is that the tentative category is right or wrong.
  • The End
  • Learning Types
  • Supervised Learning with target vector : the training data comprises examples of the input vectors along with their corresponding target vectors. Examples:
  • Classification the assignment of each input vector to one of a finite number of discrete categories or classes.
  • Regression. If the desired output consists of one or more continuous variables.
  • Unsupervised learning without target vector: the training data consists of a set of input vectors x without any corresponding target values. Examples:
  • Clustering: The goal is to discover groups of similar examples within the data.
  • Density estimation to determine the distribution of data within the input space.
  • Visualization project the data from a high-dimensional space down to two or three dimensions.
  • Reinforcement learning which maximize a reward: The problem of finding suitable actions to take in a given situation in order to maximize a reward. The learning aims to discover examples of optimal outputs by a process of trial and error. A general feature reinforcement learning is the trade-off between exploration, in which the system tries out new kinds of actions to see how effective they are, and exploitation, in which the system makes use of actions that are known to yield a high reward.

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