Andrew Ng "Machine Learning" Video Course Notes - 2 (Introduction)

1. Definition:

What is Machine Learning?

Two definitions of Machine Learning are offered. Arthur Samuel described it as: "the field of study that gives computers the ability to learn without being explicitly programmed." This is an older, informal definition.

Tom Mitchell provides a more modern definition: "A computer program is said to learn from experience E with respect to some class of tasks T and performance measure P, if its performance at tasks in T, as measured by P, improves with experience E."

Example: playing checkers.

E = the experience of playing many games of checkers

T = the task of playing checkers.

P = the probability that the program will win the next game.

In general, any machine learning problem can be assigned to one of two broad classifications:

Supervised learning and Unsupervised learning.

 

What is Machine Learning (Definition of Machine Learning):

Arthur Samuel: The field of study that enables computers to learn without being explicitly programmed.

Tom Mitchell: A program is considered to be able to learn from experience E, solve a task T, and achieve a performance measure P, if and only if, after having experience E, the performance of the program in processing T improves after being judged by P.

 

Second, supervised learning and unsupervised learning:

1. Supervised Learning - Supervised Learning

Regression: Predict a continuous-valued output based on the known correct results on the training set.

Example: Fitting a graph based on discrete house price coordinates to predict specific house prices in any situation.

Classification problem: Predict the output of a continuous discrete value based on the known correct results on the training set.

Example: According to the characteristics of the tumor (size, shape) to determine the nature of the tumor (benign, malignant).

 

2. Unsupervised Learning - Unsupervised Learning

Clustering: Divide data into different clusters.

Cocktail Party Problem: Sound Separation, Octave

 

table plaque:

From: "Statistical Learning Methods" - Li Hang

to be continue

https://www.coursera.org/learn/machine-learning/lecture/db3jS/model-representation

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