2017
Essential Math Competencies in Machine Learning
https://www.youtube.com/watch?v=1c25FFm87_c
    Pr(Y|X)*Pr(X) = Pr(Y,X) = Pr(X|Y)*Pr(Y)

              Pr(Y|X)*Pr(X)
    Pr(X|Y) = ------------
                 Pr(Y)


Raygorodsky - 2017
https://www.youtube.com/playlist?list=PL567xYdMCWxYzFfcM1Hafz5tgf1SJWBi-

Intuitively, elementary events are independent if

    P(A|B) = P(A)  // knowledge of B gives no new info about the probability of A
        also
    P(B|A) = P(B)


Multiplication theorem

    P(A|B)*P(B) = P(A /\ B)  // /\ is an intersection

From it

    P(A|B)*P(B)
    ----------  = P(A)*P(B)
     P(A /\ B)

It is better (because includes cases when P(A) or P(B) can be = 0)

So, we can come to definition

    P(A /\ B) = P(A)*P(B)