I read this introduction about AdaBoost (http://www.cs.man.ac.uk/~nikolaon/~nikolaon_files/Introduction_to_AdaBoost.pdf), and am curious why confidence for each model is defined as
$$\alpha_j=\frac{1}{2}\log\frac{1-\epsilon_j}{\epsilon_j}$$
(from page 48 of http://www.cs.man.ac.uk/~nikolaon/~nikolaon_files/Introduction_to_AdaBoost.pdf).
Could anyone provide any source for explaining this?
Thank you!