I am following CS229 course by Andrew Ng. On this lecture note it talks about using Laplace smoothing to bypass situations of 0-probabilities. What does not make sense is the immediate jump to the following line.
I cannot understand how this derivation is made. Can anyone show me the full derivation of how the factor of 2 comes into play? intuitively I feel that 2 is because it is a binary classifier, but a more mathematical reasoning is appreciated.