1.什么是机器学习
两个定义：
the field of study that gives computers the ability to learn without being explicitly programmed."
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
2.监督学习
给出的数据集中，给出正确答案。
分类：回归问题（连续）和分类问题（离散）。
3.无监督学习
没给出正确答案