Introduction
0
- Jian Tang
- [email protected]
1
- History 1950-1970 logic rules; 1980-1990 knowledge acquisition; 2010
-. machine learning
- machine learning
- use statistical techniques, “learn” with data
- extract features automatically, instead of by domain experts
- learn automatically, instead of explicit programming
- Big Data-Big Computation-Big Model : Why deep learning now
- usage
- …
2
Probability
Bayes’ Theorem
- posterior likelihood * prior
variables
- E[f] := the average value of f(X) under the distribution p(x)
- V[f], cov[x, y]
distributions
- binomial distribution
multinomial variables
- x可以取k種值, 表示x取了六種中的第三種
,對應x向量每個位置上爲1的概率
從而某個特定的x出現的概率 (也就是 )
maximum likelihood estimation
gaussian univariate distribution正態分佈
- multivariate gaussian distribution
- maximum likelihood estimation
- mixture of gaussians-可以模擬其他各種分佈
gradient descent梯度下降
- a way to minimize an object function
- : learning rate, which determines the size of the steps we take to reach a local minimum
- update equation: