Definition

Just as we judge tomorrow’s weather based on past experience, eaters want to pick a good melon from their past experience, so can a computer help humans to make that happen? If there is such a discipline, where human “experience” corresponds to the “data” in the computer, and the computer learns this empirical data to generate an algorithmic model that allows the computer to make valid judgments in the face of new situations, and that is Machine Learning.

Mitchell, author of another classic textbook, gives a formal definition that assumes:

• P: The performance of a computer program on a task class $T$.
• T: The type of task the computer program wants to achieve.
• E: Denotes experience, i.e., a historical data set.

If the computer program obtained an improvement in performance $P$ on task $T$ by using experience $E$, the program is said to have learned from $E$.