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What is machine learning

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1. Definition

   • a field of study that gives computers the ability to learn without being explicitly programned.

     - - Arthur Samuel

   • a computer program is said to learn from experience E with respect to some task T and some performance measure P, if its performance on T, as measured by P, improves with experience E.

     - - TomMitchell

2. Machine learning algorithms
   • Supervised learning
   • Unsupervised learning
   • Others
     • Reinforcement learning
     • Recommender learning

Supervised Learning

1. Definition
       In supervised learning, we are given a data set and already know what our correct output should look like, having the idea that there is a relationship between the input and the output.

2. Supervised learning problems

   • regression problems     In a regression problem, we are trying to predict results within a continuous output, meaning that we are trying to map input variables to some continuous function.
   • Classification problems     In a classification problem, we are instead trying to predict results in a discrete output. In other words, we are trying to map input variables into discrete categories.

Unsupervised Learning

1. Definition
       Unsupervised learning allows us to approach problems with little or no idea what our results should look like. We can derive structure from data where we don’t necessarily know the effect of the variables.
       With unsupervised learning there is no feedback based on the prediction results.

2. Categories

   • clustering
   • non-clustering