Another version of this: P(A|B) is not defined for P(B)=0, but you can safely let P(A|B)P(B)=0 when P(B)=0. Half the time, these two terms appear as a pair anyw

Another version of this: P(A|B) is not defined for P(B)=0, but you can safely let P(A|B)P(B)=0 when P(B)=0. Half the time, these two terms appear as a pair anyway. It's a version of "you can't divide by zero, but you can multiply the divisor on both sides of the equation and then use 0*a=0."