Naive Bayes

Naive bayes is formed from Bayes Theorem
Naive bayes is called naive as it assumes all the features are independent of each other, which is really no the case in real life

For example,
Given msg = "Dear Friends", predict if it is Spam or Not-Spam

$$
\begin{align*}
P(Spam|Dear Friend) &= P(Dear Friend|Spam) P(Spam) \\&= P(Dear|Spam) P(Friend|Spam) P(Spam)
\end{align*}
$$

[!def] Naive Bayes
$$
P(X|x_1, x_2, ... x_n) = \prod_i p(x_i|X) P(X)
$$